Selection tolerance in world coordinate length.

Hi,
There is way to set selection tolerance(SensitivityFactor) for a Select3D_SensitiveEntity in pixels.
Is there any way to set selection tolerance value in world coordinates system?.
When we set by pixels value, irrespective of zoom level it does selection. But i would like have selection in precise value of
length, not in pixels around a shape, So that the zoom level would not have any impact on selection.