I'm not entirely sure if this is what you wanted, but for the 'bullet time/super speed' demo I made ages ago, I just used (1 / timescale) to make something look as though it wasn't affected by timedelta and slowing down and all that.
global TimeFix = (1 / timescale)
.x = (.x + MovementOffset * timedelta) * global('TimeFix')
Something along those lines. I'll post the cap
(I'm also experimenting with that listbox replay method I believe Linkman made up ages ago too, I just wanted a way to do everything in slow mo, then replay it in realtime)