Yes; no need to use an external computer for the loopback with your setup since the midi in is available. Thanks for writing up the steps and adding them to the thread. For my example (since I was using C01B as my BTS preset and C16B as my BTS trigger--and routing), I believe I was routing midi in either to port B or maybe both.
At some point I might play around with embedding a sysex command to start the bts clock. However, I am wondering if it could be done with a BTS note trigger saved in a pattern template. One thing I didn't get around was the fact that in latch mode, those triggers toggle between off and on. I did play around with 1-bar mode triggers, which I suppose if I created a 32-bar pattern template with a 1-bar trigger at the beginning of each bar that would avoid the on/off toggle problem of latch mode.
I'd be very interested in knowing whatever other techniques you come up with.
Thanks for posting the question!!!! Sunday afternoon I actually used the test setup I came up with for tackling your question for some improvs as part of the Halloween event at electro-music.com. I had BTS part 1 (bass drum) latched, with parts 2-16 in 1-bar mode. While playing a usb keyboard going to the P2500 (I rotate through the channels to layer stuff), I had a blast reaching over and swiping bunches of the 1-bar trigger buttons. Since it was a Halloween event, I tried to make it creepy, but some of the comments in chat said it sound more like it was coming from a mental institution than creepy. I would not have had such fun if I hadn't been tackling your question. (It was the fun of a "madman" jamming out on the P2500--perfect for the Halloween event!!)
Steve