If you can extract just the audio from the ASF, then you could probably fix it up with some audio editor as well as converting it to a CD quality .WAV file (e.g., 16 bit, 44,100 Hz, Stereo). You could convert the ASF to uncompressed AVI (not sure what tool to use, but I know such a tool exists), then use TMPGEnc to encode that uncompressed AVI and WAV into a VCD compliant MPEG.
The tool to do it is Virtual Dub 1.3c, Microsoft made Virtual Dub take out asf support starting with 1.3d, but it shouldn't be hard to find. It'll let you rip the audio from asf, convert asf to avi, and a whole crap load of other stuff. TMPGEnc doesn't seem to like ASFs very much at all, just making it an AVI(compressed or uncompressed) might even help.