Try 'cat /proc/bus/usb/devices' and look for your scanner.
My Epson info is
T: Bus=01 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#= 2 Spd=12 MxCh= 0
D: Ver= 1.00 Cls=ff(vend.) Sub=00 Prot=ff MxPS= 8 #Cfgs= 1
P: Vendor=04b8 ProdID=010c Rev= 0.01
C:* #Ifs= 1 Cfg#= 1 Atr=40 MxPwr= 2mA
I: If#= 0 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=ff Prot=ff Driver=(none)
E: Ad=81(I) Atr=02(Bulk) MxPS= 64 Ivl=0ms
E: Ad=02(O) Atr=02(Bulk) MxPS= 64 Ivl=0ms
Look at the T: entry and notice the Dev#= number
Using that do a 'ls -la /proc/bus/usb/001/DEVNUMBER' (in my case ls -la /proc/bus/usb/001/002)
and see who's the owner. chown that to your user and it should work.
There probably is a "proper" way of doing this (and I have no problem in 10.1 OE) but you could
add a chmod entry to /etc/rc.local to make it work in the future.