The 4550 board I've been using is the one I built over a year ago using this schematic:
Except I moved the bootloader switch to RB7 (Pin40) and customized the code.
http://www.create.ucsb.edu/~dano/CUI/ is quite a good read if you actually want to learn how it works.
If you build the circuit exactly like the one in that picture, you can use the bootloader.hex from the "CUI Example Code". Then just install your LED on RC0, RB0, RB1 or RD0 etc and use one of the available hex code files.