It's fairly easy to License your Snowmobile in Montana,
You can write them at:
FWP Headquarters
Phone: (406) 444-2535
Fax: (406) 444-4952
1420 E 6th Ave.
POBox 200701
Helena, MT 59620-0701
or.....Go to their
Backup link, as well.
Snowmobile page.
Services Page.
Web site .
Direct link to Non-Residence license
If you buy a license their they have a nice secure page, looking sorta like this: