My idea was to use a three key combination CONTROL - Right SHIFT - RESTORE similar to the old PC keyboard reboot. Each of these keys is large enough to take a second pad underneath like I did with the Left SHIFT key for the Bluetooth mod. I have used the reset link from the USER PORT(line 3) and wired that in series to a switch on the CONTROL key, the RESTORE key and finally the Right SHIFT key. This is then in turn wired to Ground , so that when and only when all three keys are held down does the C64 do a RESET. Thus far it seems to be working well and from the outside you absolutely cannot tell anything is different from a stock C64.
Here you can clearly see the wire running around the keyboard fixed in place with some hot glue, unfortunately I had ran out of clear melt glue and had to use the horrible brown stuff. You need to be very careful here, too much glue, and you won't be able to close the cover properly as it sits quite snugly on top of the keyboard when the case is re closed.
The reset is working as it should do, even when using the MSSIAH cartridge. It's not something I am going to use all the time, but is a handy tool should I need to use it.