i'm the same way with my truck, anything but the transmission i do myself.
after you get the dash off you have to take the ac canister thing (don't know the name) off its bracket, take the evap case loose and pull it back till the canister thing touches the firewall and you should have enough room for the heater core hoses to clear the firewall. the only thing holding the heater core in is a bolt and a bracket that holds the hoses, and a ground strap to the firewall. when i did mine i didn't unhook the ac lines like you're supposed to because with a little elbow grease you can work the heater core hoses through the firewall without unhooking them. getting the dash off is the hardest part, after that its easy.
also when i did mine i took the steering column out and that made things easier. taking it off is pretty simple too, 4 bolts to the dash, gear cable to instrument cluster, a handfull of electrical connectors, 1 bolt holding the column to the knuckle in the engine, 3 bolts on the firewall behind the brake pedal and you can pull it right out.
some guys have changed theirs just by taking the dash loose and pulling it back, then reaching behind it and changed it, i don't see how thats possible but hats off to them.