It is pretty easy to get involved, we're an all volunteer gig [only one or two paid employees, they do marketing, pay bills, all that office work stuff that keeps us going]. Some of us work with railroads as a day job, others have no rail or even mechanical experiance but learn it "on the job". We need help with everything from locomotive repairs to car restoration to docents that act as tour guides.
The main thing, go to our site and join up [it is an insurance thing I believe - you have to be a member to do work]
www.mtmuseum.org. Then show up to the roundhouse on a Saturday and ask how to volunteer. A docent often shows interested folks the works and introduces them to the folks in the shop... Hope that helps!