sane-find-scanner
 
  # sane-find-scanner will now attempt to detect your scanner. If the
  # result is different from what you expected, first make sure your
  # scanner is powered up and properly connected to your computer.
 
  # No SCSI scanners found. If you expected something different, make sure that
  # you have loaded a kernel SCSI driver for your SCSI adapter.
 
found USB scanner (vendor=0x04b8 [SEIKO EPSON], product=0x0841 [USB MFP]) at libusb:005:004
  # Your USB scanner was (probably) detected. It may or may not be supported by
  # SANE. Try scanimage -L and read the backend's manpage.
 
  # Not checking for parallel port scanners.
 
  # Most Scanners connected to the parallel port or other proprietary ports
  # can't be detected by this program.

fax-encoder.cc: In member function 'std::string iscan::fax_encoder::operator()(const char*, size_t)':                  
fax-encoder.cc:288: error: 'uint8_t' was not declared in this scope                                                    
fax-encoder.cc:288: error: expected ';' before 'bit'                                                                  
fax-encoder.cc:294: error: 'bit' was not declared in this scope                                                        
fax-encoder.cc:305: error: 'bit' was not declared in this scope                                                        
make[3]: *** [libimage_stream_la-fax-encoder.lo] Erreur 1                                                              
make[3]: *** Attente des tâches non terminées....                                                                      
mv -f .deps/libimage_stream_la-basic-imgstream.Tpo .deps/libimage_stream_la-basic-imgstream.Plo                        
mv -f .deps/libimage_stream_la-file-opener.Tpo .deps/libimage_stream_la-file-opener.Plo                                
make[3]: quittant le répertoire « /var/tmp/portage/media-gfx/iscan-2.20.0/work/iscan-2.20.0/lib »                      
make[2]: *** [all-recursive] Erreur 1                                                                                  
make[2]: quittant le répertoire « /var/tmp/portage/media-gfx/iscan-2.20.0/work/iscan-2.20.0/lib »                      
make[1]: *** [all-recursive] Erreur 1                                                                                  
make[1]: quittant le répertoire « /var/tmp/portage/media-gfx/iscan-2.20.0/work/iscan-2.20.0 »                          
make: *** [all] Erreur 2                                                                                              
 *                                                                                                                    
 * ERROR: media-gfx/iscan-2.20.0 failed.                                                                              
 * Call stack:                                                                                                        
 *               ebuild.sh, line   49:  Called src_compile                                                            
 *             environment, line 3138:  Called die                                                                    
 * The specific snippet of code:                                                                                      
 *       emake || die "emake failed"                                                                                  
 *  The die message:
 *   emake failed
 *
 * If you need support, post the topmost build error, and the call stack if relevant.
 * A complete build log is located at '/var/tmp/portage/media-gfx/iscan-2.20.0/temp/build.log'.
 * The ebuild environment file is located at '/var/tmp/portage/media-gfx/iscan-2.20.0/temp/environment'.
 * This ebuild is from an overlay: '/usr/local/portage/'
 *
 
>>> Failed to emerge media-gfx/iscan-2.20.0, Log file:
 
>>>  '/var/tmp/portage/media-gfx/iscan-2.20.0/temp/build.log'
 
 * Messages for package media-gfx/iscan-2.20.0:
 
 *
 * ERROR: media-gfx/iscan-2.20.0 failed.
 * Call stack:
 *               ebuild.sh, line   49:  Called src_compile
 *             environment, line 3138:  Called die
 * The specific snippet of code:
 *       emake || die "emake failed"
 *  The die message:
 *   emake failed
 *
 * If you need support, post the topmost build error, and the call stack if relevant.
 * A complete build log is located at '/var/tmp/portage/media-gfx/iscan-2.20.0/temp/build.log'.
 * The ebuild environment file is located at '/var/tmp/portage/media-gfx/iscan-2.20.0/temp/environment'.
 * This ebuild is from an overlay: '/usr/local/portage/'
 *

Libraries have been installed in:                                                                                      
   /usr/local/lib/sane                                                                                                
 
If you ever happen to want to link against installed libraries
in a given directory, LIBDIR, you must either use libtool, and
specify the full pathname of the library, or use the `-LLIBDIR'
flag during linking and do at least one of the following:      
   - add LIBDIR to the `LD_LIBRARY_PATH' environment variable  
     during execution                                          
   - add LIBDIR to the `LD_RUN_PATH' environment variable      
     during linking                                            
   - use the `-Wl,--rpath -Wl,LIBDIR' linker flag              
   - have your system administrator add LIBDIR to `/etc/ld.so.conf'
 
See any operating system documentation about shared libraries for
more information, such as the ld(1) and ld.so(8) manual pages.    
----------------------------------------------------------------------

d'autre part, il faut s'assurer que le driver "epkowa" figure bien dans /etc/sane.d/dll.conf, et le rajouter si nécessaire.
 
perso, j'ai du redémarrer l'imprimante pour que tout marche...

scanimage -L
device `epkowa:usb:005:002' is a Epson Stylus NX100/SX100/TX100/ME 300 flatbed scanner

mac_gyver@Bi-Coppermine ~ $ iscan
iscan: error while loading shared libraries: libltdl.so.3: cannot open shared object file: No such file or directory