I would recommend getting a nice sling or wrap to carry him in while you work. (as opposed to a carrier) My favorite's are the Moby D wrap, and the Kangaroo Korner fleece pouch (you can get either at Peapods in St. Paul). With the Moby D you could sling him on your back while you work. Plus, with the little added weight you get extra exercise to get back in shape!
They also make toys that attach to the sling to help keep him entertained - http://www.kangarookorner.com/c-23-baby-clips-and-toys.aspx
Also, I don't know if it's possible for him to change the habit, but most babies that get worn all the time, just sleep in the sling and can sleep thru noises like a creaky floor.
As for all the advice saying letting him cry it out - that's horrible! (esp. the part about it becoming a "bad habit") Your baby has just spent 9 months entirely encapsulated inside of you, and now he's learning all about being outside of the womb. It's scary enough just not being inside - but to be without contact is traumatic for a baby.
Honestly, anyone who's concerned about your child's independence, will fare better by keeping him close when young so he learns trust. The more distant babies are kept when they're young, the more likely they'll end up clingy and needy when they're older, because they never had the bond that they needed.
You can read more about the impact of babywearing at any Attachment Parenting website (just a name for something people have been doing for centuries) -
http://www.attachmentparenting.com/princtouch.shtml
http://www.wearsthebaby.com/babywearing/babywearing.htm
I also agree with the idea of getting involved in a Babysitting Coop where you swap taking care of each others kids (usually just a few moms per group).
Good luck!