Tried that, but there is only the option to select either w2p or exe. No folder selection (only the app name appears with a checkbox).
I enclose an image of the options available in Pack custom.
I tried source and compiled. Both show the same options.
I tried Firefox and Chrome.
My env
web2py 2.18.5
Python 3.7.1 x86
Firefox 66.0.5 x64
Windows 7 Pro x64 SP1+all upd