I had an X-15 many years ago as the companion to type SGX-2000. As such, I never really needed to do much programming.
I just had a look at the manual online and I don't think the X-15 can do scenes... Because you need to be able to control the data value sent along with the CC (#34), and the effects control seems to only send off/on (0/127).
Additionally, even if it could, you wouldn't be able to track which scene was active based on the LEDs.
Also, for tuner you need bidirectional midi and the controller has to know how to process the data from the Axe Fx.
Based on the firmness of the switches (from memory) I would imagine tap tempo might be a challenge to get right.
To make it work, I think you need a momentary type switch. I didn't notice anything about that as option in the manual.