Here's the relevant part of the vmt for the heavy weapons guy, everything that has to do with shading:
---------------------------------------------
"" "modelsplayermedicmedic_red"
"" "modelsplayermedicmedic_normal"
"" "effects/tiledfire/fireLayeredSlowTiled512.vtf"
"" "5"
"" 0.01
"" 6
"" "0"
"" "1"
"" "1"
"" "20"
"" ".3"
"" "models/player/pyro/pyro_lightwarp"
"" "[.3 1 8]"
"" "0"
// Rim lighting parameters
"" "1" // To enable rim lighting (requires phong)
"" "4" // Exponent for phong component of rim lighting
"" "2" // Boost for ambient cube component of rim lighting
---------------------------------------------
This also looks like it could be helpful (skip to page 4):
http://www.valvesoftware.com/publications/2007/NPAR07_IllustrativeRenderingInTeamFortress2.pdf
Based on that, it looks like what you want is (d) on that page, that is, using warped diffuse and ambient cube shading. I believe this is a part of the phong lighting. That looks like it's what you probably want, opening that up it looks exactly like figure 7 in that pdf file. So it's a combination of the phong shading, half lambertian, and lightwarp settings that create the nice shading they've made. Rimlights are nice too :3.