Save your model as an .obj put the .obj with the textures into a folder .zip the folder and go to mixamo.com you should be able to rig it from there, me and Myke did a similar thing (well Myke mainly) with my fallout type suit
this then will save it out as an .fbx if the polys are too high download the free indie copy of simpygon you can half the poly's using this, then you can import it into blender and save it out as a .x or if you have the free copy of fragmotion
Hope that helps.
Only down side to rigging with mixamo is that you cannot legally sell the model but you can freely use it in your games otherwise I'd have posted him up for free :/ i might well have a go at some point at re rigging him using rigify in blender then i could
e.g
Intel i5 4950 Quad core 3.3ghz AMD FX 6300 x6 cores 3.5ghz(unclocked)
8gb Ram 8gb Ram
AMD Radeon 7570 1gb AMD Radeon HD 6670 2gb
and a well fed mouse on a wheel
I only smile because i have absolutely no idea whats going on