i cannot for the life of me find one

ive been looking forever and the only one ive found is for 0-1 to 3-2

Livesplit comes with its own autosplitter if you put ULTRAKILL in the game section. You have to configure the splits yourself though (you can do this any way you like)

here are some basic level splits https://www.mediafire.com/file/86ic0jvs4xryjdu/ultrakill_x3.lss/file

right click on your livesplit, mouse over open splits, and click open from file, then just select it :3 (do this after what 10_days_till_xmas said)