Either fine fishing line or dental floss. Wrap each end around a couple of sticks to grip it with and then start it under the chrome. Keep the floss or line shaped around the curve of the tank and saw it back and forth slightly as you move it up along the chrome piece. Finish off with either some Goo Gone, WD40 or something similar to completely remove any remaining sticky stuff.
Exactly as above - works a charm. I used WD40 to soften and remove the sticky residue on both tank and emblems. You then need some padded double-sided tape to stick them back on with. I got mine on Ebay, weather proof and intended for car emblems and the like.