So, I'm looking for a program that would let me take an equirectangular map and map it to a sphere, then reassign the position of the poles on the sphere and unwrap it back to an equirectangular format.

I was inspired by the planetary tilt scenarios on WorldDreamBank's Planetocopia (NSFW) and wanted to have a go at reassigning the poles and seeing what came out. I haven't been able to to find a program to do this, however.

Can anyone help me out?