SANE Configuration

First you've to find your scanner on the SCSI bus. One possibility is to use the find-scanner tool coming with SANE. 
./find-scanner -v	(as root)
will produce something like 
...
find-scanner: checking /dev/sg4... open ok
find-scanner: found processor "EPSON SCANNER GT-7000 1.14" at device /dev/sg4
...
NOTE: The device where you find the scanner has nothing to do with the SCSI ID setting on the scanner and will probably change if you add/remove devices from the bus.

NOTE: Replace the following /dev/sg4 by whatever find-scanner found on your computer.

Now a symbolic link is set to this device usually. 

cd /dev
ln -s sg4 /dev/scanner		(as root)
NOTE: Setting up the link will fail if /dev/scanner already exists.

It should look like 

ls -l /dev/scanner
lrwxrwxrwx   1 root     root            3 Jun 22  1999 /dev/scanner -> sg4
now.

Next we have a problem with the permissions on the device, check it with 

ls -l /dev/sg4
crw-r-----   1 root     disk      21,   4 Apr  5  1999 /dev/sg4

As you can see only root has permission to write to the device, which we have to do to send commands to the scanner. There are some different ways to solve that. .

In my opinion the best way is to set the sbit on the (x)scanimage executable. 
chmod 4755 /usr/local/bin/scanimage		(as root)
chmod 4755 /usr/local/bin/xscanimage		(as root)

Modify the following configuration files:

/usr/local/etc/sane.d/epson.conf 

scsi EPSON
/dev/scanner

/usr/local/etc/sane.d/dll.conf 

# enable the next line if you want to allow access through the network:
#net
#apple
#canon
#coolscan
#dmc
epson
#hp
#microtek
#microtek2
#mustek
#pint
pnm
#qcam
#s9036
#snapscan
#tamarack
#umax