I have a similar looking user port reset switch that i use with my c64c, beside mine has a pass through and ought to be quite some years old.
http://www.ebay.com/itm/Commodore-6...Instant-System-Reset-Switch-NEW-/160954197782
"if don't want to drill a hole in your pretty commodore case,but want the ability to instantly reset your Commodore 64 C64 and the Vic-20 ,then this is the tool you need!
looks really easy to build as well.
looks really easy to build as well.
It is just a switch between pin 1 and pin 3:
http://ist.uwaterloo.ca/~schepers/MJK/user_port.html