L.W.
Just curious....why can't he continue to nurse twice a day? The American Academy of Pediatrics recommends it until "at least age 2 now" and the health benefits are amazing...if you work FT I assume he is in day care...breastmilk will prevent him from being sick and keep him bonded to you. Nothing changes magically at 12 months for a child where they should be weaned in fact in most countries babies are breastfed for at least 2 or more years. Of course you can wean but I just wanted to pop in and ask the question WHY are you determined to do so.
Here are some links you should read first:
http://www.breastfeeding.com/reading_room/wean.html
http://www.smartmomma.com/Baby/weaning_baby.htm
L.