Does anyone know if I can use the Honeywell wireless thermostat (w8665A/T8665A) with a 2 wire steam heat boiler? I measured 24 volts at the 2 wire connection. I do not have A/C, just steam heat.

Honeywell says that's an obsolete product. The wiring insttructions for the receiver is here: http://customer.honeywell.com/techlit/pdf/69-0000s/69-1630.pdf

There is no fundamental reason why it can't work. The receiver must be powered so you'll have to locate power and common.

Their prestige series, I think, replaces it.