In SOP i am animating the frame param of a timeshift to warp time and create a slowmotion effect on a cached sim.
I would like to be able to reverse that timeshift by using second timeshift.
I hope to do this in chop by reading the animation of the parameter on the first timeshift and flipping the values x->y and y->x.
Another way to think about it would be to mirror a channel across a diagonal.
My chop knowledge is limited and i cant seem to find the right tool for the job.

Any suggestions?

Why do you want to do it in CHOPs? If it's a simple reverse, use the timeshift. CHOPs is hella-slow for manipulating a lot of points.