There are key factors to keep in mind when developing methods/techniques to address this threat:
1. This is a deadly force scenario. Using distance and cover to prone out suspected homicide bombers at riflepoint is the best practice. Non-compliance should be met with precision marksmanship to destroy the brain stem. The greater the distance and better the cover, the better the odds for the police to avoid injury or death should the IED detonate deliberately or accidentally. Enaging the HB-IED carrier outside rather than inside a structure and in an isolated area is the best, if possible.
2. I do not know the most commonly used explosives for human-borne IEDs in Iraq, but in Israel and other locations, Tri-Acetone-Tri-Peroxide and other peroxide based explosives are commonly used. This greatly increases the threat to law enforcement and innocents in the scenario given the dangerous instability inherent in TATP and it's sensitivity to kinetic energy.
3. Immobilizing the arms of the HB-IED carrier does not mean that the threat from the IED is negated. Aside from the threat of the IED detonating in the struggle, it is a common practice for the HB-IED to be remotely detonated by a second, distant observer. If the scenario is so desperate that a single officer is forced to engage a HB-IED H2H, then taking the bomber to the ground immediately while trying to negate the bomber's ability to detonate the IED is best as if the bomber is on the ground with the officer covering him when the IED detonates, this reduces the lethality of the blast and shrapnel to innocents in the area.
4. Usually the IED detonator is connected to the main charge in the bomb vest by wires that run down the arm to where the detonator is concealed in the hand of the HB-IED carrier. Trying to resolve this H2H is the last, worst option taken knowing that you will most likely die along with the bomber. So take this option keeping that in mind.