Paperless Office Email Button script - Show Electronic Delivery for Forms Window

I created a button script that sends out a Sales Order Form via Paperless Office. We are not using the regular printing interface because the users don't have to select the form code, and we are also writing the print/send date to UDF.

I built the script based on some examples I found on here and it works great. Now I would like to show the Electronic Delivery for Forms Window (see screenshot, a little button in the Print Window) so the users are able to change the Email Subject on the fly. It would also be okay to set the values on this form through the script.

Does anyone know how I can show this window to the user?

Thanks for your help!

Bastian