I've figured I can do a swung/shuffled clock like so:

....C2...
D1..02T98
.$bpm:80.

And this works reasonably well, but I tried this:

D1......
.$bpm:80

and this

D0......
.$bpm:80

Which should produce identical output, but reseting the bpm on each frame results in a slower overall speed. I tested this on v215 Mac sending a midi note each frame to Renoise so otherwise, no noticeable jitter. This short delay might by unavoidable, but being able to do these types of timing manipulations accurately within Orca would be very powerful.