http://www.rentron.com/Infrared_Communication.htm

Code:
PROCESSOR 12c508
   #include "p12c508.inc"
   __CONFIG  _MCLRE_OFF & _CP_OFF & _WDT_OFF & _IntRC_OSC
   #DEFINE PORT B'11111101'
	MOVF OSCCAL
	MOVLW PORT
	TRIS GPIO
		
   BEGIN
	BCF GPIO, 1     ;1uS
	NOP	        ;2uS each nop is 1uS long
	NOP		;3uS
	NOP		;4uS
	NOP		;5uS
	NOP		;6uS
	NOP		;7uS
	NOP		;8uS
	NOP		;9uS
	NOP		;10uS
	NOP		;11uS
	NOP		;12uS
	NOP		;13uS
	NOP		;14uS
	NOP		;15uS
	NOP		;16uS
	NOP		;17uS
	NOP		;18uS
	NOP	        ;19uS 
	BSF GPIO, 1 	;1uS Begin HIGH duty cycle
	NOP		;2uS
	NOP		;3uS
	NOP		;4uS
	NOP		;5uS
	GOTO BEGIN      ;2uS (26uS total for 38KHz)
	END