How to return to Subrails/Eco Mine after completing the game in Jak 3

I found this a couple years ago and found that I couldn't remember how to do it when I tried to explain it to Tomjak and Tanman. It's more complicated than I thought. There are a few important things to note. Firstly, do not save during this trick as, as far as I know, it becomes impossible to leave the temple after getting the rotator or bridge checkpoints. Also, make sure your memory card is removed, since the game autosaves upon the cutscene in the elevator starting. You cannot leave the eco mine at the end. In order to get the cutscene to not softlock you, the goal is to get the bridge checkpoint. You can do this by loading the bridge room from the rotators. The way I showed to get out of bounds in the rotator room is the easiest one I know of - the other way involves spawning at the last rotator and going back to the previous room (which is invisible but still solid) and doing a very long IFG through the roof. Camera-in-wall strats are used to load the bridge area in since the door is shut from in-bounds.