Don't use a heat pad buy some flexwatt it is a lot cheaper and better i think.Here's a good guide on how to wire flexwatt.
http://www.arbreptiles.com/cages/flexwire.shtml
It's real easy and what kind of thermostat are you using?
Buy 11" flexwatt and cut it to about 1'6" or 2' so just buy 2' of it should only cost about 7 to 8 bucks and buy 2 metal connectors.