I don't know of any applied wax/sealant that could be applied (outside of a specialty fabricator that deals with ceramic coatings) that would stand those sort of temps.
I guess I should have asked this first; what are you trying to protect from these temps?
Actually I'm not wanting to use it to protect the items from heat, just wondering if there was a polish/sealant that would stand up to the heat (for looks). Didn't figure there was, but as I'm getting ready to have it all off of the car I thought I would ask.
Your best bet is to take it to a shop or some place that polishes and let them polish up real nice witha machine and then you can keep it looking good polishing it by hand throughout the summer.