the apa is not necessary for the modem to lock. If the dish is properly aligned to the correct beam, then you can connect the modem directly to it, and it will lock.
I do it all the time. I have a WB dish setup at the office, we connect the modem, let it update firmware, lock... and occasionally provision, all without an apa.
It does the same thing as if the modem gets unplugged or whatever, you plug it back in, give it a minute or two to lock, and thats it.
O, and just so ya know... where our office is located, we are on the borders of 3 beams. We use 3 different beams in our service area depending on what part of the area they live in.