Gnomad is a software to sync Creative Nomad players on Linux, new version 2.8.3 has basic MTP supprt and "should" work on T serie and other MTP enabled player, provided libmtp 0.0.2 is installed.
Unfortunately I was unable to compile libmtp 0.0.2 and could not test my T-30, if someone managed to transfer files with Gnomad on iRiver players please let me know! Site says that it "Perhaps" works on iRiver T10 and T30 (untested!)
This is an important step, when the libmtp will be more mature it will no longer be necessary to change firmware in UMS in order to use T serie players on Linux and surely a port to Mac will follow shortly.
If you want to test Gnomad:
http://gnomad2.sourceforge.net/