Record MIDI, begin playing recording while still recording

The scenario:
I want to start recording MIDI, then hit play and begin playing back the beginning of the MIDI recording while not interrupting that recording process.

I started off with [seq] which is very handy except if you start playing your recording it stops recording any subsequent events.

I've thought about recording into a [buffer~} but that seems messy.

I've been trying out [mtr] but the only way I've though of doing it with that object is by setting a length, setting it to play @loop 1, then using the "addevent" messages to write at certain times, but I don't think you can get the current playhead position of the [mtr] object.

thanks for your thoughts