Steering Wheel Control Interface

I like how my questions are not worth answering. Would it make a difference if I told you I was an electronics engineer?
Ask people about their “luck” all you want. It won't necessitate that YOUR system will work nor will it accomplish your goal [if it is] to hook up your steering wheel control interface (SWC) while keeping OEM button functionality. Thus you are asking a question, that from my estimation, is not going to give you the answer you are looking for.
I can help you figure this issue out. However you have to be willing to 'follow.'

All that said, let me try this again. I will try to be more specific. Please read the questions carefully, answering wholistically and from an objective perspective.
1) Why do you want to know if anyone has “had success?” If something will work it is irrelevant if other people got it to work IMO. (If anything you should be asking if anyone has had problems installing a similar device. FYI - Potential is not limited by past occurrences.)
2) What model of SWC do you have. (The page you linked has 10.)
3) If it is easier or more compatible can you return your model and buy another?
4) What make and model HEADUNIT do you have / are you planning on using?
5) You say you are very familiar with electronics. What specifically does that mean? Can you solder, read simple / complex schematics, understand the function of components and small parts, etc?

Almost anything can be made to work in the world of electronics.
1) Is $100 an acceptable number for you?
2) How about 20 hours? Does the time limit include sourcing parts?
3) Can you, specifically, point to what brought you to the conclusion that the volume knob would not work? I read the technical documents and did not come to that understanding.

Please number your responses. Answer only the question asked. If further clarification is needed please include the information after the correlating question or in a separate paragraph at the end. This will help you get the correct answers and limit confusion.

androitcaptor,
Would it make a difference I worked on these cars when they were new? Not really. I know there are alot of folks here with valuable input. As requested, numbered responses.
First post:
1) YES, I do! Why else would I be purchasing an SWC interface?
2) The average price on the PAC website is about $85. That is a good price point.

I felt as though both questions were rhetorical based on your preface, therefore, I did not answer. I did receive input from another member that helped. There wasn't any condescension, just constructive input.

Second post:
1)I was just trying to get ANY feedback that didn't bicker about the semantics of my post.
2) PAC SWI-PS They were specific to groups of headunits.
3) I just wanted to know if anyone had worked with this unit. The search function revealed very little info.
4) Sony Xplod CDX-GT550UI
5) I have a strong knowledge in electronics. I can solder, read schematics, etc.

PART II
I understand one can make anything work. I was looking to see if anyone had luck with this type of unit.
1) As stated before $85 is fine.
2) I have fifteen minutes invested in looking up the parts, not including this post.
3) The box contained another website with vehicle specific information stating the volume thumb wheel would not work. I wanted to know if the alternate programming of the buttons would work. If no one had luck with it, then I would return the unit.
http:www.pac-audio.com/swixprogramming

Any additional constructive input would be greatly appreciated.