Check out the DYI section for consumers. Their is a fee and its good for a year of use. Or I recomend the FSM.
As far as an other sites..??
Here is the quick run down:
If you have A/C it must have the freon removed.
Disconnect the heater hoses
Remove the a/c heater plenum mounting bolts on the engine side of the firewall.
Disconnect all electrical connectors and vacume hoses from the plenum assembly
double check and remove any connections or wires.
Drop the plenum assemblyy down and out.
Split the assembly and remove and replace the heater core. clean the inside as required. and reassemble.
re-Install in reverse order
Now this was a real quick how to. You will need a manual, either check the above from alldata, or check a auto parts store for one as last resort.