We can't explain the universe, just describe it; and we don't know whether our theories are true, we just know they're not wrong. >Harald Lesch
To clarify the process of extending supply:
You preplace an extended unit (= player number > 12) which causes a buffer overflow which in turn alters the supply readings in sc.
The player number and the type (unit or building) decides which type of supply (Available/Limit/Used and Zerg/Terran/Protoss) of which player it affects.
E.g. A unit for player 157 adds to player 1's Zerg Available and so does a building for player 73. (2nd list)
The unit/building itself (Marine, Ghost, Barracks, etc.) decides the amount of supply that is added. (You can't subtract)
E.g. A Terran Marine adds 25 supply. (first list)
==> When you preplace a Marine for P157 it will add 25 to P1's Zerg supply Available counter.
In SC the supply is displayed in the upper right as
Used/
Available (e.g.
4/
10 when you start with 4 workers and a Nexus). The supply cannot go higher than the
Limit. (200/200 by default). So generally it's the Limit and/or the Available you want to change.
Fartys tool is an easy way to find out the correct player number, then you just have to go through the unit/building list (1st list) and decide which you choose.
The neat thing about the whole process is that this unit only has to be present at map start. If you kill it afterwards the extended supply will still be active! That's why Terran buildings with low HP work so well: They die right after map start.
Finally keep in mind that if you choose to place a unit (not a building) you can't access all supply variables because for some you would need a player number greater than 255 which isn't possible. So in that case you could only place a building.
When maps only crash Mac users it's likely because the map used EUDs. Those directly read sc's memory and the memory banks are different on Macs so in some cases it just doesn't work and in some cases it even causes crashes.
Set doodad state has a number of uses (check rockz' link). Its
intended use, however, is to open and close doors (doodads of the installation tileset).