I used a Roland R-26 recorder at a jam session this weekend and got some good sounding tracks off of it and want to mix it in Sonar.  The unit is actually a 4 track recorder with two integrated mic's and then 2 additional inputs for external mics/instruments.
 
I only had one cable to run from the mixing console and picked up the left channel out into one of the external inputs on the device to get more present vocals.  The room mics picked up all the instruments...but the vocals are usually way behind and hard to mix off of a recorder like this in a loud room.

Anyway, the track I pulled off the R-26 ended up being a stereo track but everything is panned to the left (since I was using the left output of the mackie console in the practice room).  
 
How can I turn the stereo track into a mono track?  

choinga
 
How can I turn the stereo track into a mono track?  

Is it possible to create a bus and route that bus to the master out, set the interleave of that bus to mono and then route the track that you recorded to the left channel to that bus.

Bounce To Track(s), select Split Mono. This will create two tracks; one with the vox and one with the empty audio of the stereo track. Delete the empty track, delete or archive the original stereo track.
There may be other ways of doing this in the X series. I'm about a decade behind.

57Gregy
Bounce To Track(s), select Split Mono. This will create two tracks; one with the vox and one with the empty audio of the stereo track. Delete the empty track, delete or archive the original stereo track.
There may be other ways of doing this in the X series. I'm about a decade behind.

There are indeed several options, but yours is simple and effective.