Bhop was patched in 2010 with the orange box update ABH is the remaining method. Firstly, you need a way to jump super quickly, you can do this with an AHK script [wiki.sourceruns.org] or you can use some custom binds by typing "bind mhwheelup +jump;

After that, angle the pallet next to the cart of Hopper mines, and then put the pallet at the proper angle, GBBH (Grenade boost back hop) hit the pallet, jump off it and air strafe into the entrance. There are some rocks in HL2/HL2E2 that have a proper su

ABH is the ability to jump backwards and gain incredible, unnatural speed. Hl2 and Eps, Portal 1 - NOT Portal 2, L4Ds, TF2 or Counter-Strikes Gmod has been patched.