I was about to say, "doesn't Home Studio only support two simultaneous tracks of recording," but a quick look onthe Home Studio - SONAR compariosn on Cakewalk's website seems to suggest that's not so.
Now in my SONAR 2 Audio dialog box, the playback and recording devices in that pulldown are labeled as "Playback Timing Master" and "Record Timing Master." The actual devices themselves are enabled by selecting them on the Drivers tab. Try that. Then see if in the track properties you can select 1/2 or 3/4 on a track-by-track basis.