I purchased my ORV sticker online, and figured I'd do a little "how to" for the folks like me coming from out of state:
Go to:
http://www.mdnr-elicense.com/welcome.asp
Once there, scroll down to the certification block, and click myself. DO NOT worry about the requirements...click certify and move on.
Customer log-in screen will now come up, scroll down and you will see a series of circles you can select..
select : non-michigan resident
Put in your birthdate, and on the right side select FREE MDNR (this allows you to buy the ORV sticker)
It will take you then to the shopping page, and you can select the 16.25 MAIL ONLY ORV selection.
After that you will print off your MDNR and reciept pages (after paying) and once you give your address the sticker is on the way.
Hope this helps!