You generally meet antenna rules by connecting some sort of reverse biased junction to a substrate or well tap. If your goal is to junction isolate individual building blocks, e.g., through nested well structures, you need to get your antenna rule checker to not complain about missing substrate diodes when placing a building block, to be integrated into the entire chip layout later, into a junction isolated well entirely. [EDIT: Luis Rodavalho correctly remarked that I don't mean antenna rules per se, but related (latch-up?) rules that may require nets to be connected to wells or substrate] This is an entirely solvable problem, but probably will make the PDK and tool chain a moving target, subject to change (and reinstallation) at-will, "for good cause, or bad cause, or no cause at all", unless you try to think ahead or wait for others to do the tool chain bug minesweeping for you.