1.27mm pitch connectors are a **** to assemble without the correct crimp tooling, clone crimpers are mostly a pile of cr@p, and the official crimpers will cost you an arm and a leg, so follow Dan's advice but the other way round. Buy a six way cable with 1.27 mm pitch connectors, cut off one end and either solder it to a 2.54 mm pitch header, and reinforce and strain relieve with a bead of epoxy over the joints, or crimp on 'duPont' pins and fit to a six way shell (clone crimper kits to do 2.54 mm pitch 'duPont' style connectors are affordable and if used with care give reasonable results).
Another option would be to make an adapter using this pitch adapter PCB:
http://www.proto-advantage.com/store/product_info.php?products_id=3800052You don't appear to have clearance round the 1.27 mm pitch header so cant simply fit a female 1.27mm pitch header socket to go straight onto your board's header. You probably need to get a 1.27 mm pitch cable as above, but instead of cutting the end, simply put the mating header on the pitch adapter PCB.