Button that makes a normal mount take off (jump in macro form)?

I’m looking for a way to be able to “take off” with my normal (nondragonriding) drake. This would be a macro button that simulates pressing the space bar to jump.

I’m sometimes positioned in a way that I can’t reach the keyboard but do have the wireless mouse available, so I’d like to be able to mount and take off with just the mouse. As is I have to kind of find a ledge to run off of to try to convert it to flying mode instead of walking on the ground.

You could use a keybind.
Options->Keybindings->Movement Keys->Jump
Leave spacebar in the first column and add a mouse button to the second column.