does it works ? and if it is, can someone tell me a keys ?
Are you referring to left alt and right alt key? That's not possible.
I've done a bit of this by resorting to an external keymapper. I use Karabiner on macOS.
Basically, ST can't do it (to my knowledge), but you can arrange the keymapper to remap your combo to something ST can differentiate, before it reaches ST.
May be you can write some hack with Keypress using ctypes:
thanks for info