clock question

i have some code that sets the internal clock to 8 mhz

"InitialiseOSC
movlw b'01110010'
;run mode,8mhz,internal rc block
movwfOSCCON"

what i need to do to get this pic to run at 4mhz
i have never used a pic that runs an internal clock i use crystal to set the clock

any help is as allways appreciated

ps:the pic is a 18f2321

The OSCON section of the data sheet will give all of the options.