Don,
The HobbyCNC boards haven’t had the timer feature for quite some time.
Unfortunately, I can’t help you with answers regarding the GMFC software – you’ll need to ask them what work-arounds they suggest. The USB/Ethernet to parallel port devices I’ve see are all software-dependent, so what works with one CAM system likely won’t work with another.
Sorry, but I’m sure the GMFC folks (or perhaps the website) can give you an answer.
Regards, BrianV