I haven't personally tried this but it should work:
Ataish - the guy who makes Wax also has Frameserver with which you can use Virtual Dub to play a file that is currently on the Vegas TL - and the part I haven't tried - apply VirtualDub filters
You can also render it first in VirtualDub as a AVI then open the filtered file in Veas. Just remember its uncompressed so you'll need pleny of hard drive space if your porject is sizeable.