Well, you shouldn't be able to smiply pick a fixed number of tech levels to have at the beginning; if starting-tech was handled that way, everyone would always pick the two other colonization techs first and then there'd be no point to having three different planet types. It'd have to be something based on research points; you get a fixed number of bonus research points to allocate immediately.
The game already works like this, to a limited extent; players start with 20,000 research points to spend on the first turn (I don't see a line configuring this in settings.txt, is it based on the starting resources for the game instead?). As far as I know, virtually everyone puts that into researching frigates.
Cranking this up to a much higher limit would allow a player to research multiple new technologies on the first turn, essentially giving them initial tech levels. The only limitations I can see with this would be that you could only research a maximum of 12 "initial" techs (four for AIs), and you can only research one level for each one using the starting research points.
The latter restriction can actually be somewhat useful; we could make colonization techs impossible to grab for "free" by adding a cheap first level to those tech areas that doesn't give the ability to colonize that planet type just yet (not sure what it _would_ give, the ability to colonize a planet is pretty all-or-nothing). Unfortunately, though, it also means that one couldn't skip straight to (say) nullspace cannons by dumping all the starting points into astrophysics and grav tech.