There's a kind of loop each side where the handle is attached to the bag. Just put a 10mm od alloy tube through there and cable tied the bagman attachment to it. I put some black heat shrink and end caps on the tube to try and make it tidy. All in about £6 for the bits on ebay.
Actually does anyone know of a good source for all the geo data on the Pompetamine? Found a few geo charts now and they all seem a bit different.