Wow - it should be simpler than this, shouldn't it?
Here's what I would do in a situation like this - I would put a physical phone someplace out-of-the-way, where no one would want to use it for inbound calls. (IDF closets, etc.). Then, I would give that station the X-port extension you're currently dialing for the help desk. Just in case, I would also set the call-appearences on the phone to NOT ring.
Now that the number belongs to a real, live physical station, callers should be able to transfer to this number by just pressing 0 during your Audix greeting.
Susan
"Opportunity is missed by most people because it is dressed in overalls, and looks like work."
- Thomas A. Edison