hi J. Newport,
here you have a one second exact! rutine, sorry the commments are in
spanish, but it works fine any way :) i have no time to translate it
now.
if you need longer time intervals, just call the rutine several times
with a loop or keep the count in a register every time it finishes the
routine.
regards
juan.

;****************** RUTINA DE RETARDO DE UN SEGUNDO ********************

un_segundo
Y     EQU .207 ;VALOR PARA UN SEGUNDO
X     EQU .254 ;VALOR PARA UN SEGUNDO

XF     EQU 12 ;REGISTRO DONDE SE GUARDA EL VALOR DE X
YF     EQU 13 ;REGISTRO DONDE SE GUARDA EL VALOR DE Y

;FORMULA GENERAL   T= CXY + 3XY + BY + 4Y + A + 1

; DONDE T= MICROSEGUNDOS,
;X= CONSTANTE
;Y= CONSTANTE
; A= RETARDO ;CONOCIDO
;  B= RETARDO CONOCIDO
;  C= RETARDO CONOCIDO.
; EN ESTE EJEMPLO, X=207, Y=254, A= 1, B= 0, C= 16

; PARA X = 1; Y = 1; A=B=C= 0   T = 0  +  3  + 0  + 4  + 0 + 1 = 8 us.

; PARA X = 207; Y = 254; A=1, B=0, C=16  T = 841248  + 157734  + 0 +
828  + 1 + 1 = 999,812

 MOVLW Y
 MOVWF YF

     ;DELAY (A) =1
     NOP
LABEL1
     MOVLW X
     MOVWF XF

 ;DELAY (B)=0

LABEL2
     ;DELAY (C) = 16

     GOTO $+1  ;2 us.
     GOTO $+1  ;2 us.
     GOTO $+1  ;2 us.
     GOTO $+1  ;2 us.
     GOTO $+1  ;2 us.
     GOTO $+1  ;2 us.
     GOTO $+1  ;2 us.
     GOTO $+1  ;2 us.

 DECFSZ XF,F
 GOTO LABEL2
 DECFSZ YF,F
 GOTO LABEL1
    ;return
 END