Recall some time ago we were playing with tire valves stuck in 1/2" holes drilled in PET bottle caps (well, *I* was anyway), and using that to "pressurize" keg-filled to-go bottles. Turns out these same tire valves mate perfectly with the inflating needles used to pump up footballs etc. Just screw the threaded part of the needle into the rubber underside of the valve.
The next trick is to bore a small hole alongside the main hole in a #2 (is it?) drilled stopper -- the kind that fits in a bottle opening. I used a red-hot sewing needle but perhaps you can come up with a better way, or drill out an *undrilled* stopper with an off-center 3/8" hole and perhaps a 1/16" or smaller hole. It needs to be small enough diameter that the valve needle "seals" as it's inserted. Make the hole such that it doesn't poke out until it gets to the bottom -- no peeking through the sides!
Push the needle through the stopper from the top (outside the bottle) just so that the hole at the end of the needle is completely visible outside the other end (inside the bottle) of the cork. Now assemble the rest of the PMCPB as normal. THe valve and the beer line will jockey for position but there's enough room for everyone; it all seals inside the cork anyhow.
You'll need an air chuck on a hose attached to your keg. I leave one permanently attached (along with a clamp since they do leak). Now, you can purge and pressurize your bottle before filling. Purge by leaving the stopper loose while giving it gas, or do a few pressurize / burp cycles. Now fit the stopper in tightly and pressurize for real. Open the beer valve; you'll get a little beer since some pressure escapes when you remove the chuck. Now, to fill, use your fingernail to press the pin in the valve slightly and slowly to gradually relieve the pressure. The beer flows on its own as the pressure is relieved. When the bottle is full, close the beer valve, and press the valve pin completely to relieve the rest of the pressure.
I just finished bottling four APAs for our club's July 13 competition, and regret that I didn't bottle more as it was EASY. Minimal mess, about 10 minutes out of my busy (yawn) day. Much easier than those gigantic commercial C3PO-looking monstrosities that cost $50 or more.
BTW I used room-temperature bottles and normal keg pressure (~10 psi) and had absolutely NO foaming from a well-carbonated beer.