Url: http://www.pushok.com/soft_sccdispatcher.php
I use a number of source code providers for different projects.  Unlike the great SCC Switcher on codeproject (which is down today for some reason), this one acts like your SCC provider then allows you to choose on a check-out by check-out basis which one to use.  This helps me because I switch between SCC multiple times a day and remembering to switch from one to the other works great.  Check it out.