Check out shashwatak's github project satellite-js https://github.com/shashwatak/satellite-js
It's an accurate enough implementation of the SGP math model Scott mentioned for what you need.
Also successfully implemented in jeyoder's ThingsInSpace webgl project: https://github.com/jeyoder/ThingsInSpace
and a few other places around the web if you poke around. 
Cheers,
-frank