toilet training a ready but lazy 2 1/2 yo...

my son, who's 2 1/2 has been telling me for months that he wants to go "wee-wee potties mummy" but is much happier doing it on the carpet!! about 2/3 of the time he'll go to the potty, and we have a toilet seat and stool for him, and he loves not having a nappy on, and toilet training, but its getting frustrating now!! and when he wants to do a poo, it "mummy, poo, nappy please." he doesnt like the splash-back... it scares him. i have never pushed him, just hoped... i cant afford 3 in nappies!! i dont care about night-time, but want him toilet trained in the daytime. i talked to the child health care nurse, and she agrees that he sunds like he's ready, just lazy. he'll go to the potty, but not if he's playing or anything like thaqt. i've tried biog boy jocks, which he picked out, but he thinks their a nappy too. my SIL reckons that she got hers out of thathabit by letting him walk around in his wet jocks for 20 mins or so before she changed it, he only did it 2 or 3 times before he learnt its not nice... anyone got any suggestions??!!!

You try a reward for him for when he does it in the right place. Half a jelly bean or something. This works well for Angus but he still forgets he doesn't have a nappy on sometimes.