You can copy/paste, then select notes and drag them to the proper root (and adjust 3rds, etc.). For triads I do not find it much quicker than redrawing them though.
Sans a chord track generator, I talked to the gentleman who had created this "
Key Chords" site, and he graciously modified his site to include an "Export MIDI" button in the middle of the GUI. If you select key in the upper left, it exposes the most common chords, which can then be drag/dropped into the rectangular section at the bottom. With the BPM set properly you can set each chord to 8 beats (for your case in the OP). Then "Export MIDI" with the "Structure Only" left checked (gives full duration MIDI notes for each chord). That MIDI can then be drag/dropped into your SONAR project for use.
Unchecking Structure Only tries to emulate the strum pattern, but at the point I last spoke to him that was not working properly (and he did this for us on his own dime).