Hi all!
I'm afraid I won't be modding the mce module filter-brightness-als.
I've just now noticed that the source code that was advised here (twice, if you consider my reposting) is for MEEGO mce. Although related, it's NOT the module that is used in Maemo. From an article on a blog (http://cool900.blogspot.co.uk/2009/1...n-maemo-5.html) I gathered that Nokia moved parts of other proprietary software into MCE (I hope that was done in order to open the sources for that other stuff), but as a result MCE was open-source in Diablo but is a proprietary bit in Fremantle. Pity.
This wiki page contains details:
http://wiki.maemo.org/N900_Resources
Unfortunately the CSSU doesn't contain reimplemented MCE sources. At least it's not findable.

It should still possible to do what I have in mind by at least 2 ways
- adapt the MeeGo mce to fremantle. Hard to do since the maemo mce is a black box and it would be really hard to properly test that the replacement is doing everything the original did.
- patch the Maemo MCE binary - basically edit it in hex replacing the bytes that are responsible for brightess thresholds and levels. Considering the circumstances, this should be much easier to do and less risky.
However, I won't be able to do that until I repair my usb port because MCE es an essential part of the phone OS and breaking it would most probably require a reflash, which I can't do at the moment.
For now I'm limited to exploring the binary. Sorry.

Edit: found it! In filter-brightness.als.so, at offset 0x8378, in small endianness, there it is: the struct containing the ambience levels and their corresponding brightness. Will keep you posted.