Assigning MIDI Knob to Control Session Tempo

Well, it depends on how exactly you imagine this, I mean, if you just want to have tempo changed without its value being written to the tempo track, it is certainly achievable using the midi remote. Let me know if you need a guidance on this.

However, if what you’re after is actually writing these tempo changes, things get ugly.
I did try to implement it using the MIDI Remote, however my final attempt (which is actually part of my Novation SL MK3 script) is not giving smooth results, thus abandoned (at least from me).

Here’s a video demonstrating this and the issues involved:

And the snippet for the MR can be found in a reply to a relevant thread here: