Alas, the Tascam FW-1082 is never going to work with Snow Leopard because Tascam/Teac have discontinued support for it. I'd already been disappointed at reading the addendum on this page:
http://www.tascam.com/article;34,2034,3800.html
And I got the following mail reply to my inquiry to Tascam (downgrading to Leopard I would do, but I will not downgrade my Mac Pro from 12GB RAM to 4GB!):
Dear Mrs Noort,
Due to a general incompatibility with Apple's new 64-bit Audio Core engine, which cannot be resolved through an updated driver, we have decided to stop further driver development for the FW-1082.
If Final Cut Studio 3 runs on Leopard (OS 10.5..), there should be no problems in conjunction with this program.
The driver v.1.60 will work under Leopard up to a max. system RAM of 4 GB.
Best Regards,
V.Asmanidis, TASCAM Support