Not possible right now, at least for some elements. Here is a summary from another forum post:
Alpha - already included
CESSENTIAL_Direct - already included
CESSENTIAL_Emission - already included
CESSENTIAL_Indirect - already included
CESSENTIAL_Reflect - already included
CESSENTIAL_Refract - already included
CESSENTIAL_Translucency - already included
CESSENTIAL_Volumetrics - already included
CGeometry_NormalsDotProduct - invisible suggestion: should be visible (see Arnold example image)
CGeometry_NormalsGeometry - invisible suggestion: should be visible (see Arnold example image)
CGeometry_NormalsShading - invisible suggestion: should be visible (see Arnold example image)
CGeometry_UvwCoords - invisible
CGeometry_Velocity - invisible suggestion: should be visible (see Arnold example image)
CGeometry_WorldPosition - invisible
CGeometry_ZDepth - invisible suggestion: should be visible (see Arnold example image)
CInfo_NetworkRenderDebugging - n/a
CInfo_RenderStamp - n/a
CInfo_SamplingFocus - works as expected
CMasking_ID - invisible suggestion: should be visible
CMasking_Mask - invisible suggestion: should be visible
CMasking_WireColor - invisible suggestion: should be visible
CShading_Albedo - invisible
CShading_Beauty - already included
CShading_BloomGlare - already included
CShading_Caustics - n/a
CShading_Components - already included
CShading_LightMix - already included (rest unassigned)
CShading_LightSelect - already included (rest unassigned)
CShading_RawComponent - already included
CShading_Shadows - already included
CShading_SourceColor - invisible suggestion: should be visible
CTexmap - invisible
(Internal ID=477530807)