Several ways come to mind
Easiest: Use the Enable Buy/Build option accompanying Insimenator.
This method keeps Buy/Build enabled until you exit the lot, after which the enabling goes away.
Or: Use this cheat when on the lot (don't let the word dorm throw you off, it doesn't apply only to dorms):
boolprop dormSpecificToolsDisabled false
Don't forget to set it back before leaving the lot:
boolprop dormSpecificToolsDisabled true
This may or may not work for some types of lots in Apartment Life.
Or: try the flavor of enabler (keeps buy/build on permanently) which matches your EP/SP set-up here:
http://simswithcomplements.googlepages.com/mods.htmlThe Bon Voyage flavor there should work up to and with Apartment Life but as with any hack, the hack itself may conflict with other hacks you already may have.