Attached Link: http://www.chaosmarch.com/3dmodels/modlist.cfm?FType=&faction=1

I looked for similar stuff recently. I found a site that had a number of battletech mech models, none specifically for poser though. I'm working on poserifing one of them. Also DAZ3D has a mech for sale, though it won't be easy to make a good texture map for it (take a look at the template) though solid colors are fine.

http://store.daz3d.com/catalog/product.php?pcode=ps_ch024b