Still can't control the brightness, but it doesn't really matter as the LED backlight only consumes about a watt. Much more important to turn all unnecessary devices off to save power. As I've got the TG with the radeon chip that consumes 9W of power even when sitting idle, and pclos has better support for the Intel graphics, that's been a priority for me.
There must be a way, because other distros have managed it. Possibly it needs a custom-compiled kernel.