Yes. Say you want to use template key 2234 for c3 and template key 2590 to c4. Your generic legislative lookup page is something like
http://salsa.democracyinaction.org/o/ORGANIZATION_NUMBER/blastContent.jsp.
Just insert "/t/" and the template key number right in the page URL after your organization number. So your c3 lookup page would be
http://salsa.democracyinaction.org/o/ORGANIZATION_NUMBER/t/2234/blastContent.jsp, and your c4 lookup page would be
http://salsa.democracyinaction.org/o/ORGANIZATION_NUMBER/t/2590/blastContent.jsp.
That may vary slightly from salsa.democracyinaction.org depending on what salsa node you use, and you'll need to put in your unique ORGANIZATION_NUMBER.
This is a handy way to change the template for any number of Salsa pages just by altering the URL a bit.