Take one jar, put, say, 5 pieces of pasta in it. Your child can earn extra bits or have them taken awawy and (in our house) after a week the pasta is exchanged for 10p per piece and then the jars reset at 5 pieces.
I use a combination of token jar and star chart, depending on the type of behaviour I'm trying to modify. Pasta doesn't work on some kids because they don't all relate it to reward (it's just another crappy food to my ds), so you might need to try something else (I like the smarties idea). We're currently using pretty sea shells - small ones for everyday successes and dirty great big ones for major achievements.
Soupy, this seems to be the ideal place to thank you for the pasta jar idea. Read one of your posts about it a couple of weeks ago. Ds being a little so & so at the time. Have implemented the pasta jar idea and have darling little boy back (most of the time ;) ) Thanks