I don't use PT but I can imagine this might be simpler than generating a new beep every time... although I could be wrong.
The best way to figure this out is to mentally list the individual steps required to fulfil your objective and then translate them into a sequence of Keyboard Maestro actions. Something like:
Select menu (File→Imports→Audio...)
Pause until button enabled "Open"
Navigate to path of beep file (AppleScript pehaps? I can help with this)
Select "Add Button"
Press "Open" button
...etc...
If you get stuck along the way, let me know the exact steps you need to perform manually and I (or someone else) can help you get them going with KM.
But, here's what i don't understand, if i want to assign a macro on KM for this action, let's say F18, i create an action, set a keystroke, entering the command.. well, doesn't work. It creates me a blank region. Strange...
Any idea how i could manage to do that with just the F18 ?
I'm French, with a French keyboard, maybe it's because it doesn't work?
If I type the 3 on the numeric keypad, it doesn't work. (I mean, the combination control shift option 3)
If I type it like this, with the " (which is the same key as 3 on the top part of the keyboard here) it works fine straight in Pro Tools, but the macro doesn't... Really weird...