Aha! Thank you very much! scrStealItem is exactly what I was looking for. Thanks.
EDIT:
What does " global.equipped[8,1] = true
global.equipped[8,2] = true
global.equipped[8,4] += 1;"
mean? It's different for each item, and I have no idea how to use those. If it helps, I'm using the fanmod for YASM 1.6. (I don't plan on releasing this)
That's the array for the worn item inventory (cape, shoes, etc) in YASM. It's initialized in scrClearEquipped.
item 8 = Jordans
8,1 = does the player own them?
8,2 = if they are currently being worn?
8,4 = quantity owned (added by fan mod, so you can sell extra gear you pick up)
In hindsight, the inventory system was designed very poorly. It's functional, but not modular. I've wanted to add new items to the mod but my lack of forethought and sloppy coding have made it unappealing. In this case, the length of the inventory arrays are hard coded, when I should have set their length in a global variable when they were initialized or used Game Maker's built-in data structures. Apologies.
EDIT:
How about a mindfuck? Check the YASM 1.6 fanmod scrScumGlobals script, line 15. Change the value to 1. It works, but there is no item pickup for it.