If memory serves me correctly both Skids and Rusty were brainwashed by the MLF after being captured by Freedom Force (when the rest of the New Mutants went to Asgard). They were taken to Avalon by Exodus where they were cured by Magneto and become part of his Acolytes.
Rusty was killed when Holocaust (from the Age of Apocalypse) was brought on board Avalon and after being rescued Skids went to University.
Skids is now working for S.H.I.E.L.D., and Rusty was briefly brought back as part of Selene's Techno-Zombie army in the Necrosha storyline. I can't remember if he "died" again or is one of the few to "survive" and is on the loose.
I'm sure if I've missed something out (or have got something wrong) somebody will correct me, but I think that's everything that happened to them.
How did this happen? Was this some part of Civil War that I missed?
Anyway, thanks for the info, amigo!