How do i enable the in-game timer for individual star runs? I could not find anything mentioning that anywhere on the page or in the rules.

Collect all 131 stars in the game, activate hacktice from the pause menu and enable only the timer

Look, grab the 131 stars (3.4) and there are 2 ways, the first is with the hacktice app, which is on github by aglab2 and the other is a cheat that you add to the Project64 emulator