I dunno OSCTUNE, but modifying the .INC file usually work for me

You have 2 choices for PPL, but I think if you use 4mhz it would be "normal" speed.

here is my config for a 18F2550, using 20Mhz xtal, so this has to be high speed mode(HS)

; __CONFIG _CONFIG1L, _PLLDIV_2_1L & _CPUDIV_OSC1_PLL2_1L & _USBDIV_2_1L
; __CONFIG _CONFIG1H, _FOSC_HSPLL_HS_1H