N64 Multi-region question

Gidday Guys,

I don't nearly post here often enough but this one is about making a multi-region N64 by wiring up the PIF chips - actually in the same way as described here on this forum

http://assemblergames.com/l/threads/n64-pal-ntsc-mod.53108/

What I was left wondering while I was reading about this and trying to figure out how accurate the pinout was (using my cheap archaic tools) is:
-Is this one of those chips that is disabled by disconnecting the VCC and GND pins? Has anyone tried or is it folly for me to even bother with experimenting while I'm undertaking this mod?

I'd suspect that it's not the kind of chip to have a simple method as someone would have done it...right?

 

Inside my multi region n64

 

Now that is high-resolution gold! It's also pretty self-explanatory as to what's going on, but I find it odd that there are four analogue switches there when three would suffice. I'd love to see the underside of the board (if possible) as it'd allow us to start piecing together where the traces go.

What I also found unusual with that mod is that pin 25 has been cut and joined to the EEPROM dat. The mod I was working on survived fine until I started messing with that wire in particular. Long story short: I did succeed in making a simple PCB for a multi-region unit and even started working on a V2 of the design, but the the unit that was was experimenting with has died and I'm out of money to pursue this project any further.

Too add to this pool of knowledge, I got an email from a friend pertaining to what that microprocessor in the middle there could be doing:
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Right at boot, either the first or second thing the PIF does is send a signal for the region it is. If the CIC doesn't respond with the corresponding signal it should lock before anything else happens (for instance, before IPL2 is loaded to PIFRAM) Pretty sure NTSC is 110 and PAL is 100, but that info is second-hand. An MPAL PIF has never been examined as far as I know, but since they're compatible with NTSC carts fairly safe to say they report the same.

IPL2 sets S4 to the region used by software, independent of the initial check. That's how bootloaders are able to change the detected region around. That doesn't guarantee the software is going to appreciate you doing that, of course.

Also, the main CIC<->PIF runtime algo alters nibbles in reverse order. Pretty sure the 7xxx series does high nibble to low nibble, and the other series all do low to high. Might want to double-check that too, but should be the case. The results have to match between the two or the system will lock.

Ideally, you'd just want to program a new PIF that avoids region checks altogether. It's an SM5-based chip--just like the CICs are--and there's an assembler online. Seems like an awful lot of work though for something that can be solved easier software-side.