For enable bump on p_MegaTK go to 'Normal(Bump)' tab and enable 'Use Input Normal' checkbox.
Create bump2d or bump3d node(dependent what texture 2d or 3d you'll use). I'll create bump2d.
Create texture, for example 'cloth'. Connect it to your bump node by default (cloth1.outAlpha to bump2d1.bumpValue)
Connect bump node to p_MegaTK shader to 'Input Normal' (bump2d1.outNormal to p_MegaTK1.input_normal). Please don't connect texture directly to 'Input Normal'!
Render... You'll get bump without filtering.

Bump witout filtering
For enable bump filtering we should convert p_MegaTK shader to maya type using p_maya_shadingengine shader
Create p_maya_shadingengine shader and connect it to p_MegaTK1SG (Shading Group) instead of p_MegaTK1
Connect p_MegaTK shader to p_maya_shadingengine (p_MegaTK1.outColor to p_maya_shadingengine1.inColor). In other words you should insert p_maya_shadingengine between p_MegaTK1 and p_MegaTK1SG.

Bump network Graph
Don't render! Enable 'Export with Shading Engine' option on Shading Group. This option inform mental ray that input will be maya's type "RGB, RGB, RGB, RGB", but not "RGBA". After enabling it Maya will apply filtering for this shader.

Shading Group
Render...
Bump without filtering | Bump with filtering |
Warning! If you are using p_maya_shadingengine shader or any maya's native shader on miMaterialShader slot you should always enable 'Export with Shading Engine' option, otherwise Maya will crash during render.