Jeff
To participate as a driver in The Winter T Tour, with your Model T, you have to register and pay the tour fee of $175. The tour was full, but has some cancellations.
Some visit and ask to be a rider for free in a T if an accommodating participant will allow you. Some just follow along and visit the T's when they are at the daily destination stops.
This link has all the info:
http://www.tinlizziefl.com/winter-tour.html