Not being familiar with the script, I know only two
ways to stage a hanging that pose no threat to your
actor.

1) The noose is NOT ATTACHED to the hanging
rope. Placed around the victim's neck like a
necklace, the victim is dropped through the
scaffolding, out of sight of the audience, onto a crash
pad. The rope is long enough to be left dangling
below the scaffolding and is yanked taut at the
bottom of the fall by an accomplice.

2) The hanging rope is attached to a harness (like a
parachute harness or Peter Pan flying harness)
concealed beneath the actor's costume. The rope is
run up behind the victim's collar. Once again, the
noose is NOT ATTACHED.    This method allows the
actor to be hanged in full view of the audience, as his
chair or trapdoor is kicked from beneath him, he is
supported by the harness.

Please note: in both cases the noose MUST BE
SEPARATE from the hanging rope to avoid any
possible danger.

Good luck.