userAccountControl is an additive parameter, so it's made up of x + y + z to determine which permissions etc the user has. For example, if a user has a value of 512 (Normal), the value for "Password not required" is 32, so to set the account to not require a password, set the userAccountControl to 512+32=544
You can get a more comprehensive list of the codes from
http://www.computerperformance.co.uk/ezine/ezine23b.htm