Today I wrote a proof of concept program called "mikmod2rpp" (requires libmikmod and WDL). Most of the code in there is based on the Gravis Ultrasound driver for MikMod, but instead of uploading the sample data to a soundcard, it writes it to .wav files, and instead of playing the samples on the soundcard, it writes a REAPER project file (RPP). It is not perfect, does many things wrong, but it's somewhat usable.

Here are a couple of test projects (which include the mod/xm as well as the converted files): spathi.mod (from SC2), and resistance_is_futile.xm.

In case there's any question, it turns out the tracker format is incredibly efficient for both editing and playback... compared to a DAW.