Ok grabbed a console from Game Traders and have done this with a 4.433619Mhz 4 pin oscillator to a MD2 (VA1.0 but that don't matter).
4.433619Mhz 4 pin oscillator
Where to connect 2. Cut here 1 disables the existing frequency to allow for the new one added. Cut here 2 disables the encoder mode (PAL/NTSC) to allow for us to connect pin 7 to GND to lock the encoder in PAL mode.
Connect the oscillator
Switch in PAL
Switch in USA
Switch in JPN
3 position 4 pole switch (2 poles shown, 1 pole used) note pin "2" is not connected as this is USA (so no connection).
When I mod the next one (my VA2.3 Genesis needs a LED as the original was broken) I am going to wire up a bi-colour LED (red/blue) to switch between the different regions on one of the other spare poles. So PAL will be red, USA will be blue, JPN will be purple.