After a lot of mucking around with the older pdaxrom-builder stuff I finally got a working kernel toolchain going, and compiled a couple of modules for beta3/pdaXii13:
/lib/modules/2.4.20/kernel/fs/udf.o - for reading UDF format discs from a usb-connected dvd drive - just don't expect to be playing DVD video though.
/lib/modules/2.4.20/kernel/drivers/usb/dm9601.o - If your dongle is recognised by your current driver there's no need to change to this one. But a few USB device id's are missing from Meanie's pdaXii13 build of this driver, including the one from my dongle. Originally I got around it by hex-editing the original driver and replacing another ID with mine, but the result wasn't exactly releasable If you got a "USB device X (vend/prod 0xXXXX/0xXXXX) is not claimed by any active driver" error in dmesg with the old driver and the device ID is one of 0x0a46:0x6688, 0x0a46:0x0268, or 0x0a46:0x0668 then this build should sort you out.
Make sure to do a "depmod -a" after installing either of these.