Dont use an impact to remove bolts from aluminum! The threads will get
pulled out with the bolts. Also be carefull with which bolts you apply
heat to because some have a very specific heat treat. Get a "longer
ratchet" and make sure your sockets are the warrantied type. (dont use
12 points)

The harmonic balancer bolt is threaded like any other. Turn it counter
clockwise to remove but you will likely need about a 4 foot long
ratchet/breaker bar (dont use torque wrenches for removal) and someone
using a tool to hold the flywheel/flexplate. Before you put most of
these bolts back in put "a little" Anti-Seize on them unless they
require a locking/sealing compound.

JackCat@webtv.net (JacktheCat Turkey) typed until their fingers bled,
and came up with:

use a real impact wrench.

I had to use an IR Titanium impact to get that one loose. I've done the
big breaker bar thing, bracing a block of wood in the pulley to keep it
from spinning, and it is a major PITA.  It is torqued to 155 ft lbs -
the highest torqued fastner on the car.  

Been there, Done that, have the T-shirt

air tools.

I get a product called Kroil from www.kanolabs.com (only available
mail-order and internet). I buy a gallon at a time and thoroughly saturate
all bolts to be removed. Rarely have lost a bolt that way.
The harmonic balancer can be a bit of a pain to remove but most often just
needs a serious impact wrench. I had one for $40 that worked ok but the $200
thunder gun (1/2" drive) is amazing.
I gave up the propane torch years ago. I have a oxy/acet set now but did use
mapp gas in a turbo torch for a while. Far better heat output. Aluminum has
much better heat flow than steel so any heat you put in one area tends to
flow away unless you use a lot of heat in a small area.
As with any repair, a general knowledge of how much force you can exert on a
bolt before it breaks is often learned by experience. Sometimes just
cracking it loose is only half the battle. Keep adding a good penetrating
fluid and working the bolt back and forth to remove it without stripping the
aluminum threads.