Hi Trilyan,
Did you ever find a solution to this problem? I just purchased a Microsoft Reclusa. Great keyboard, but I have the same problem you do. I have found that if I install either the Intellitype Pro 7.1 drivers, or the Reclusa 1.05 drivers, only the volume knob works with MC15. I can't use either of those drivers to remap keys it seems, and remapping programs (such as KeyTweak or SharpKeys) do not pick up the Reclusa's media keys. The best I have found thus far is to use the custom mapping in the Reclusa software to remap the right-hand NEXT/PREVIOUS buttons (labeled R4 and R5) to CTRL + N and CTRL + L. That works, but only if MC15 is in the foreground. If something else is, then they have no effect.
If I uninstall the Reclusa drivers, (same goes for Intellitype), then oddly enough, the Play/Pause, volume, Next Track, Previous Track buttons all work in MC15. But if I do that, then of course, I can't use any of the remapping options with the Reclusa software which is the reason I bought the darn thing in the first place. So I am stuck. Either I get Multimedia key support but no reclusa drivers, or I install Reclusa drivers but can't have Multimedia keys.
Have you found a better solution?
Thanks,
DD.