Using the High Altitude Sensing Board with a handheld radio

I know that somehow it is possible to use that board (http://www.sparkfun.com/products/9944) with an actual hand-held radio. I was just wondering how it could be done and what would be needed. It’d be awesome if it could do RTTY right off the bat. I’m an electronics hacking noob and figured with my ballooning stuff, this would be a fun addition!