I use an Immersion Chiller with a water recirculating system. Equipment:
1) home made IC - 25' copper coil
2) pond pump
3) 50qt cooler
4) 3-4 gallon of cold water
5) ice (store bough in summer, harvested snow/ice from yard in winter) Process
1) At 5 minutes prior to end of boil, kill heat source and whirl pool by manually stirring
2) load up cooler with ice and water
3) At 0 minutes insert starsan soaking IC into pot
3) Start pond pump to start the IC working
4) I usually let the first couple gallons of real hot water empty into sink or another bucket to reuse for cleaning
5) I then redirect the return water back into the cooler, and add ice as necessary
6) Usually gets to 65F in about 25 minutes
If I'm lucky, Santa will bring me a march pump and then I'll make a "mr malty whirlpool chiller" to augment this process.
Good luck and let us know what you end up doing.