If you are only looking for power, then run a 12V line/or with a converter with whatever Volts you need for the monitor through:
fuse box->inline fuse->converter(voltage adapter)->A-pillar ->sun visor.
Same place can be used for AV cords as well.
I would recommend not to tap into the homelink wires. They are lower gauge wires and may not be suitable for you monitor. I'd rather run a slightly higher gauge wire with an inline fuse with lower rating.
There are empty slots in the fusebox. I used slot 4 or 5(I forgot) with an inline fuse, voltage converter and ran a ground cable to the a screw near the glovebox for my iPhone charger and aux purpose.
This setup will allow you to run your AV cables to the glovebox so you have minimal wire mess everywhere.
Be careful in running the wires through A pillars, DO NOT obstruct the air bag path.
Also, how are you planning on powering the PS3? inverter or something?