I've read and programmed many Orions but only from the back panel connector. I never had to put it into any special programming mode.
I wasn't aware that there even was a mic port programming cable for an Orion. While it is possible to program an MDX or a 500M from the front panel, no GE documentation I have ever seen gives any indication of a mic port programming cable for an Orion.
There is an optional extended options programming cable which provides an HD15 connector that can be used for programming from NEAR the front of the radio, in a remote mount configuration.
You can go to repeaterbuilder and start browsing the many Orion manuals if you wish, but I've already done that and none of them that I've read indicate that the mic port can be used for programming.
Here, start with this one, which specifically references programming cables:
http://www.repeater-builder.com/ge/lbi-library/lbi-39175a.pdf
At this time I am inclined to think you have been given false information. I do not think that mic port programming is possible with an unmodified Orion.
If' I'm wrong then I would have very much appreciated finding the right answer, oh, about fifteen or twenty years ago when I first started using Orions. Using the DB37 programming cable is usually something of a chore. Not usually very convenient at all.