Okay, I have a bunch of Pokemon ROMHACKING tools, and an hour to kill. Let's make a custom Firered rom. When we're done, I'll distribute the ROM for everyone to play..

First off: the starters.
Post ending in 1 decides the grass starter, post ending in 2 decides the fire starter, post ending in 3 decides the water starter. They can be any Pokemon (doesn't matter what type), as long as they're available in gen 3 and non-legendary.