Have you heard of a sport called bikejoring? It's bassically what your looking for, except the dog are in front of the bike instead of beside it. It's also more expensive thaan the springer setup. Basically it's running a sleddog team but with bikes, or carts. A single dog setup, multisport harness $25, bike stem $20, tug lines $20.
I run a two dog team, and purchased all of my equipment from Adanacsled Equipment (www.adanacsled.com).
Hope this helps out, oh btw, something I learned the hard way. I didn't teach my huskies basic mushing command to begin with, what a mistake that was. They went every direction but where i wanted