Original build seems to be a tribute to Sub-Zero from the Mortal Combat series.
Now the OP is in need of Force damage instead of Cold damage.
Exactly how to go about doing this is unclear, since applying force damage spells to unarmed attacks are hard to make optimal.
Anywhere near optimal actually.
EDIT: AFB, what level does the EF get to cast and deliver touch powers as part of a full attack?
Level 3 for touch spells, level 7 for ray spells.
I can't think of any good Force-damaging spell at the moment, except Orb of Force and that's not applicable here.
@tealjohn:
So, what you want is a level 20 character that augments his punches with Force Damage?
The way I see it, you're stuck halfway between someone who want to punch face and someone who likes killing stuff with magic.
Being stuck there isn't fun, since nothing you'll try will really work adequately.
If you want something that will put down the hurt in melee whilst still having magic as "backup", take a good look at Shapechange.
Or a decently built Monk/(Psychic Warrior or Ardent, whichever you prefer), punching 6 attacks at 12d6 damage each.