In the Materials Lab, select the small arrow at the top of the screen to open the Shading Mode menu, Select Blend Transperancy. In the OPTICS section of the Material Lab, check the 2nd dot next to transperancy and set the component to picture(Click the "P"), import your transmaps into the Picture Editor, load your map into the first box, then click copy, goto the 2nd window(where bump maps go) and click paste, click ok to delete current selection. Click the Exit checkmark and return to the Materials Lab. This process will have to be repeated for each body part the tansperancy map is applied to.