Platform shouldn't matter, looks like all you need is the jet pack cheat.
I think I can explain this. The gym has no ceiling in it's collision model, so a jet pack takes you through the false one. From
here you can find all the interiors, they're placed way above the map (around 1000 units w/ player position active). When I
first got the strategy guide I thought the weapons maps were flawed because thy showed weapons that weren't there until I
started playing w/ script mods & the position mod. Turns out they're right where they're supposed to be, just out of reach.