As far as the backlight goes there are only 6 settings for it with the pdaXrom, this is the same with the Guylhem rom but with the Guylhem you could manually edit the brightness into the conf file at any level between 0 and 255.
You should be able to open the device using a userspace program and then choose any of the levels (I can't remember how many there are off the top of my head), this is all a lot easier with 2.6.x using the /sys entries. Take a look at the code, either for my version of bl-0.0 from GPE or at libopie2 from Opie to see the exact devices, etc. (I imagine the info is also somewhere in the pdaXrom build system, I just don't know where).
I would like to be able to build a script that would say, up the clock speed, then run a CPU hungry app, and then put it back to normal after the app shut down.
Again, 2.6.x will be a pleasant surprise for you; using cpufreq you can choose from a variety of in-kernel governors which will handle this automatically, or you can handle it all in userspace with something like cpufreqd.
i tried qclockchange but it seg fault when i try and the System overclock only has 3 modes 416 520 624 i want a lower mode like 208 and 104.
Have you tried looking at the source code? I shouldn't think it'd be very hard to hack something together. Regarding your choices of frequency, I don't know what your pxa270 (going from the freqs you state) supports, but you could take a look at the pxa270's source file in the 2.6 kernel source and see what settings cpufreq is allowed to use - this will tell you what frequencies are available.
Si