Emulate pressing Axim x51v joypad center button?

[pro-fit]

Anyone know the code to emulate joypad center button?

Long version:
In Excel Mobile I've automated activating the "Menu" menu, and then (using keystrokes recorded with Calligrapher's PenCommander) scrolling to and activating the "Edit" item on that menu. This opens a submenu through whose items I can also automate scrolling.
That done, if I physically press the joypad center button, the command for the currently highlighted menu item is sent to the application/system (foreground window).
I want to automate pressing this center joypad button, thereby eliminating the need for further user interaction.
This is part of a Copy and PasteSpecial>Values procedure involving formulas and multiple sheets with formatting differences.
By mapping this to a hardware button I've reduced 20+ stylus taps to a single button press (assuming I can overcome this last obstacle.)
I have all the tools needed to implement this, but I can't identify the value of the message generated by the center joypad button.

Any clues? Thanks in advance!