Well, yeah. You could check to see which heater hoses are hot and which aren't, your heater control valve to see if it's working. Also the blend doors/actuators/controls.
As far as how hard it is, I've seen easier ones. Do you have Air Conditioning skills and equipment?
Go here;
http://www.autozone.com/shopping/repairGuide.htm
then select your Year, Make, Model, and Engine, then click the links for Chassis Electrical, Heating And Air Conditioning, and Heater Core