Hey Sam:
First thanks for joining and becoming a part of OUR FAMILY. That's exactly what we are here. No show-offs, no nasties, and if there are any, they get da boot! Just plain simple folk who have a common love and interest, and love to share their knowledge with others.
Secondly, as you've found out, most engineering companies were separate entities and were known in the army as bastard units. They were attached to corps, armies and when needed to individual divisions, etc. This is exactly the situation with the VI Corps engineering units.
Third, I do not have any information regarding this unit at the moment, but that may change. However, I strongly suggest that you follow a few leads that I suggest in my research section.
http://208.109.212.45/forum/index.php?showtopic=23 (all addresses, phone numbers and websites are listed here)
Number One: Get in contact with the Office of History, Army Corps of Engineers. While it cannot be guaranteed, they have folders on most of the engineering units. They had a ton of stuff on my dad's unit, the 540th, so give them a shot. Please tell Mike Broadhead that I sent you. We are good friends, and he was a tremendous help to me.
Number Two: Get in contact with NARA in Maryland. Go there yourself, or hire a private researcher or research student from one of the colleges. NARA will have records from WWII. There was a wealth of info on my dad's unit. I can tell you more if you decide to pursue this route.
Number Three: Contact Richard Horrell at WW2 Connections. He does private research and has an EXTENSIVE library at his disposal. He works on several levels. Check out his website.
Hope that helps to get you off to a good start. Happy to help. Best of luck to you.