OK... I understand your problem! You could try just heating up the one pin where you want the connection and inserting a wire like this:

http://www.ebay.com/itm/40pcs-20cm-M...item20ef967429

But... If you want, we can make a small change to the firmware to watch which ever limit switch you want to use. What would happen is the printer would get the M600 filament change command and do its thing. After you get the filament changed and the nozzle purged of the old filament, you would press and release the specified limit switch. And everything would continue on its way. Do you want to try that?