I was able to rent a harmonic assembler from oriely's for $50 and it worked prettily slick.
I've never seen the harmonic balancer come apart while the motor is running. But I've heard that it you use a gear puller rather than a harmonic balancer puller you will only pull off the outside of the balancer. Just what I've heard ya know.
By the way...it's not too good of an idea to use an impact with a sticky trigger on the crank shaft pulley bolts. I didn't think much of it when I was doing it but the trigger stuck and it doesn't take much to strip out those threads. Luckly I was able to tap the hole out to 3/8-16 and put in a corrisponding bolt. Thanks to the shop classes I've had it saved me another $60 bucks.