http://www.webos-internals.org/wiki/...to_Get_Started
They present 2 routes - quick and relatively painless, just what you need to get apps on. Or more in-depth that gets you root access to your phone for...whatever you feel like I suppose.
If you go the "easy" route, skip down on the page that it links you to, past the "PreBrew" section straight to the "WebOS Quick Install Method" section.