HTC RC E160 / Creative EP 630 Zombie Headphones - sounds good!
Thanks for the inspiration.
As one can get the HTC RC E160 really cheap (EUR 4,50), I ordered two and gave it a try. In contrast to the OP, I did not manage to make proper connections to the small printed circuit - glue all over, and everything much too tiny for my soldering skills...
I found it much easier to just swap the speaker capsules with an old EP 630 (which had a broken cable, my family's standard earphone). Both the HTC's and the Creative's capsules open really easy, and you already have stripped, tinned wires and nice (not so tiny) soldering pads.
Just be careful when pulling out the cables and don't forget to re-add the knots before soldering.