I agree with Rosy, in fact iwas about to post a similar answer, as its quick and easy. Another variation on this method of layering is fill some 4" pots with soil or compost and sink them into the ground under your creepers, just slightly proud of the ground. twist the stem to give it some slight damage, if it breaks 1/2 way through thats fine. Peg it into the pot and place a egg sized pebble on top for good measure, then give it a year to become rooted then cut the stem from the parent plant and plant out to their final positions..