Bump works, it just works differently.

In most Renderman (which includes 3Delight and to a lesser extent Firefly among others) render engines Bump gives you an apparent amplitude based on the setting. In most other render engines (to include Iray and Carrara) bump is based on relative size of the UV islands compared to the surface area they take up.

The 3Delight to Iray conversion converts to a smaller value because it can, and does, cause seams on the textures for figures like V4, and Genesis 3.

For Iray, or Carrara or others, If it is one UV island, or the ratio is 1 to 1 then just turn up the bump. If there are multiple UV Islands and they are different material zones then the bump will need to be adjusted individually.

Note this, usually, does not have the same problem when you use Normal Maps instead of bump maps.