For Perms it's normally control points but what I do is only ride Perms I can find someone's GPX track of (owner or someone who's already ridden it). So, I still follow gpx track but do the receipt thing at the specified controls (rather than validate it by sending a complete gpx file).
I don't think I quite understand Permanent events
For example:
http://www.aukweb.net/perms/detail/AC15/
Does this have a fully defined route? Or do you just have to ride between the controls?