I'm not sure how it being a module changes it. Personally, I see it as a misfeature, but it should otherwise be configurable through sysfs, which works whether the code providing it is a module or built-in.
I'm not sure about binary module sharing etiquette, but here's the one I'm using with 2.6.28.10-cssu1: https://gist.github.com/Maxdamantus/.../omap_hsmmc.ko Edit: caveat: with this module as-is, if the SD card is removed, you'll have to reboot before using the slot again. It looks like it does state resetting and stuff when the cover is closed, so someone would need to spend some time doing more than a one-line modification to make it work neatly.