Biab don't have any way to drag and drop midi in, so you need to do it in RealBand or a DAW first. You can open your SGU song in RealBand or with a stereo mix of the other tracks in a DAW, create the drum track with MT Power Drums.
Once you have the drum track created, save it to midi or drag the track number to DROP MID.
In Biab, File > Import Melody from MIDI
Choose Ch 10
Go to Piano Roll M (Melody) right click select all notes > Cut
Go to D (Drums) > Paste
While notes are still all selected (red)
If the notes are note aligned to correct beat hold Shift and drag the beginning of fist note to bar 1 or Bar -1 if you have a count-in.
Freeze track.