And depending wich PIC you're using you may have 1,2,3,... Timer/Counter who can work with external Clock. Be sure the PIC you select provide you at least 2 of these with external Clock Source.

Or there's still this interrupt on something stuff.

@Sayzer
@ DEVICE HS_OSC,WDT_ON,PROTECT_OFF,CPD_ON,PWRT_ON,BOD_ON
You know what i want to say now