So far, I haven't found a way to edit it. At the point that I discovered that PECTAgent wouldn't connect to HTTPS, I was still in testing and thus was able to reinstall. Now the issue has cropped back up (after applying some updates) and I'm trying to figure it out again. Too bad I didn't take better notes...
Scratch that... I just remembered (after reading my initial post again) that the PECTAgent.ini file that is in the bootwiz folder (<Deployment Share>\Task Handler\bootwiz\oem\DS\winpe2\<x64/x86>\Base\Program Files\Altiris\Altiris Agent) is where I found to change how PECTAgent connects. Hope this helps. Sorry I didn't notice your response sooner. You'll have to regenerate your PXE images, but changing the port to 80 instead of 443 should do the job. This is also where I tested/verrified using https for the protocol had no effect.