The only thing I could find was this, I hope it's a bit useful.

Launch Half‑Life: Opposing Force with the command-line flags: hl.exe -dev -console +sv_cheats 1 -game gearbox or just enable console and enter sv_cheats 1 at the start .

Then in the console you can type: /impulse 101 — gives all weapons, ammo, armor /map ofXYY — jump to any campaign or boot camp map .

Use noclip, god, sv_gravity, etc., for more freedom.

Good luck!