Puller is by far the best method. Heating isn't really a good idea in my experience as it can damage the new bearing if you get the case too hot and if your only changing the rear bearing you can damage the cage on the front bearing.

Also without an insertion tool it is possible to slightly misalign the front and rear bearings even if using the crankshaft to install.
Try to find a buddy with a puller/insert tool (or invest in one as they pay for themselves very quickly!). You won't find the pros using the heat method!