No tutorial, but...
The general consensus is to roll a little ball of greenstuff, coat it lightly with oil (was it vegetable oil ? something inconspicuous like that) and press it to the detail you want reproduced. Then let it set. You\'ll have a \"negative\" of the detail, and now you can press another ball of GS to your \'cast\' and voilà, instant detail !
If you need a full part (as opposed to just one side), it gets trickier ; I guess you could press two oil-coated balls of GS but I wonder if it wouldn\'t give you a pretty bad mold line in the end...
P.S. From experience, I think it\'s better to write full information in the title of your topic instead of cutting it of at the important part with a \"...\"