Render the image you want as either a tif or Psd. In Photoshop create a new file, with a transparent background, 91 pixels wide & 91 pixels high (NOTE: In ProPack you could make the pixel height higher - good for full length figures etc. I'm not sure about P4 or P5[haven't tried it]). Open the Render and go to the channels palette and CTRL click the alpha channel (this will select the object and NOT the background). Copy and paste this into your NEW file, arrange/transform until you have it as you want it, then simply 'Save for web' as PNG 24(with transparency checked! The PNG has to have the exact same name as the related CR2, PP2 etc - except for the file extension - that it is related to.