Nick,
This, as you realise is a sticky one. whilst normaly I would simply explain what has happened and the difficulty of removal, I have had qualified sucess on a few occasions.
First cool the stain with chewing gum freezer spray, then with a towel just dampened with a suitable solvent, such as Solval, gently dab at the stain for a few seconds, untill tranfer starts to occur, then blot with a dry towel, repeat a few times then cool again and repeat.
This is a very slow process, requiring a lot of patience and no guarantee of sucess but if it makes you a superstar and leads to more work, may be worthwhile.
Best of luck,
John.