Two words:
ice vest!
Get these flat ice strips/sheets and cut/arrange them around your chest and shoulders. Keep an extra couple sets on ice in a cooler.
http://www.rubbermaid.com/rubbermaid...d=HPProd100629
You can get a little sheet like that at Target for just a few dollars.
Don't put them directly on your skin, of course. Instead, take an old shirt and fashion pouches for the ice with duct tape.