I don't know how you managed to find no previous threads on this.
I didn't feel the need to post up 100+ threads
https://www.newschoolers.com/web/forums/readthread/thread_id/170743/
https://www.newschoolers.com/web/forums/readthread/thread_id/379257/
https://www.newschoolers.com/web/forums/readthread/thread_id/344305/
https://www.newschoolers.com/web/forums/readthread/thread_id/331152/
https://www.newschoolers.com/web/forums/readthread/thread_id/280268/
https://www.newschoolers.com/web/forums/readthread/thread_id/279358/
https://www.newschoolers.com/web/forums/readthread/thread_id/140559/
https://www.newschoolers.com/web/forums/readthread/thread_id/72831/
https://www.newschoolers.com/web/forums/readthread/thread_id/34320/
https://www.newschoolers.com/web/forums/readthread/thread_id/12274/
https://www.newschoolers.com/web/content/search
Twoods has done it a few times - he posted some info about it:
https://newschoolers.com/web/forums/readthread/thread_id/148163/
Basically:
"don't prime it, don't clear coat very much
I had a whole thread that I explained it in but I can't find it anymore because of the new searchbar
Basically, start out cleaning it with some grease cutter and if you have it, denatured alcohol.
sand it to make it a little rough, with like 100 or 120 grit sandpaper. not too rough.
Spray like 5-7 VERY light coats of KRYLON BRAND FLAT WHITE on there,
the last coat should be just enough to cover up the graphics. The idea is that you spray so thin that the paint dries almost instantly upon touching the ski. You don't want wet paint that will set up into layers that will crack and flake off when the ski flexes.
after that, wipe it down with a dry cloth and use sharpies to decorate it.
then, use a VERY LIGHT coat of clear coat to seal the sharpie. "
Could also check
http://www.clevermill.com/paintingyoursnowboard.html
It seems krylon is the most commonly used as it bonds to plastic very well.