Thanks, Dan - I first glued the foam roadbed to the oak plank and screwed the oak planking into the wooden shelving it sits on and then used #4 screws into the FT and through the vinyl roadbed to hold the track in place. My experience is that FT doesn't shift around a lot, especially on straights, so I only insert screws every other track piece and every piece on curves. I countersink the holes a little and then back the screws off a bit, also.
Being OCD, I have to then paint the heads grey so they blend in.
Lionel say it carries FT track screws, but I don't know if they actually have them or if anyone has ever tried them ?