basically, start the chamber as normal then portal peak a portal onto the roof and then quantum crouch launch up, place a portal out of bounds then teleport to next to the elevator and PQR back in bounds, I discovered this while messing around with quantum crouches. the demo explains it better, took me few attempts :/ Demo: https://drive.google.com/file/d/1-OHFcFIAUFZivfuxXjIsm6ApG7IcRBNf/view?usp=sharing

i can tell u one thing: its much slower than the main route

i also discovered a variant in chmb19 and its similar to the pre-steampipe route, tbh, i think inbounds and oob should have pre-steampipe and post-steampipe categories, i can tell you 1 thing tho, oob on post-steampipe will have A TON of quantum crouches