Instead of teensy, you can get arduino pro micro and save a bit of money. It is a lot harder to program though, especially for a newbie.
To program, basic steps are:
1. download teensy loader for your OS
2. download soarer's hex file for his converter
3. follow guide on teensy loader page to flash (at this point KB should be usable)
4. open up soarer's documentation
5. figure out what keymap you want
6. write changes to to a keymap file
7. write new keymap using soarer tools scas and scwr. (now KB is usable with your custom keymap, layers and macros)
I am sure ezrahilyer will have more complete info once his guide is done. Looking good so far!