ive been doing it for about 2 months.
you got it right.
render each track individualy as wave or aif and at pro tools you have to convert them to p.t. files and to the same bit/sample rate.
to match up you have to always beging render from beginning of project for each track.the grids are almost perfect beetween the 2 programs but not exactly.
whats cool is anything thats a multiple of 30bpm(i.e. 30/60/90/120/etc.)is always a perfect grid match.

Yep...I've just done this recently and you're right on the money.

Make sure you zero out every track...no FX, reset all audio and pan envelopes to O, set all faders at 0, etc.

It also helps if you export every track starting at the beginning of the project. Even if your song doesn't start until the 3rd measure, include all audio from Measure 1, Beat 1 (or 00:00:00:00.)

Then export each file as an .aiff. When they import it into Pro Tools, they can line up all audio clips all the way to the left and all tracks will sync up perfectly.

I did this and also added two quick metronome clicks at the begninning of every track (armed every track and recorded it all at the same time. Now I know my version of Vegas can record 36 tracks of 24-bit audio at once!) This serves as an additional audio (and visual) reference that the tracks are lined up.

Rob