We are renovating our laundry room. We have a single plastic sink that my
wife wants to hang from the wall rather than use the base that comes with
the sink. Are there any kits available that would allow us to use the
existing drain setup?

How about buying a ready to assemble base cabinet from Home Depot and
dropping the sink into it, leaving off the original base (plastic legs ?)
In normal circumstances, you should be able to put the cabinet right where
the sink was and use the existing plumbing. This finishes off the sink
nicer as they aren't too "pretty" on the outside.