I posted a thread about this the middle of last year... can't seem to find it now though...
But after like 7 months of running this process, all the consoles I have modded have all worked excellently!
I built my contraption into the expansion port on my V10, but on my brothers console I created a switch box which plugs into the console.
I am now working on a bistable timer circuit with IR support using a 555Timer IC and a Low frequency IR Filter IC... Seems to be going good, I just need to finalize the IR Circuitry...
As for your 'Relay'... it is not needed... There is not enough voltage to cause an electrical cascade, just using the DPDT and a Momentary switch will surfice. You can't just add diodes to the Motor pins either, you wouldn't be able to reverse the polarity...
PS2 V5 w/Magic 3, 40Gb HDD, Sony NA
PS2 V7 - In Bits (Used for testing)
PS2 V9 - Custom Switch Mod/MC Exploit
PS2 V5 - CC1.1, 300Gb HDD, Sony NA
NGC - Viper
N-Wii - WiiKey