wow, didn't figure on such an amazing response.
I did it exactly the same way as I clone normally. Soaked the rockwool overnight in plain water (ph'd to 5.5, as this takes the alkalinity out of the rockwool), sprayed the leaf twice a day with luke warm water, also ph 5.5. I keep the water luke warm by leaving it close to the light. Usual diagonal slice across the stem. I also like to groove the tip of the stem, but on saying that I don't think it makes much difference.
The cloning gel I use is really cheap. I buy them in a pack of six, usually you are meant to place a cutting straight into a pot... but I empty all the pots into a larger container and use this as my rooting gel. It's by a company called gel2root. 2.99 (pounds) for six pots. I can't see myself ever needing to buy rooting gel again. Each pot contains 125ml of rooting gel.