I've implemented the DOS sounds. I had a look at how I could possibly go about doing the DOS music; the one possibility seems to be swapping out BassMod for the full-fledged Bass, plus using the plugin for that that allows WinAmp input plugins, and finally combining that with the Winamp in_vgm plugin... a lot of work... (Plus, I've had zero luck with simply the first step of that, swapping in Bass... best result I can get is compiling without error but not playing any music.)
(The one alternative option is to instead use looped OGGs, which still requires swapping out BassMod for Bass, and will result in players about 8MB in size, at least for orig; OhNo and Xmas/H94 will be significantly less due to having far fewer tracks. By comparison, the above option would only increase the size by about 500KB.)
I did consider the option of converting the VGMs to a more BassMod-friendly format, but while there's a convertor to convert XM to VGM, there doesn't appear to be anything in reverse. There is a VGM to MID convertor (and MIDs can then be converted to IT or XM very easily), but the output results tend to not sound too much like the original track...