The general idea is to have some kind of fax emulation software installed that offers you a "printer" which is really fax output. I.e., if you install WinFax or such, then from any Windows app such as word you can pick "File", "Print", and among the available printers pick the WinFax printer, and instead of going to a printer that output will go out your modem port in fax format.

WinFax offers a COM interface:

oFax = CREATEOBJECT("WinFax.SDKSend")

So, you can automate all of that. I know there is an example of this somewhere on UT. I'm pretty sure it is a class called FoxFax.PRG.