You dont install it but flash your motherboards BIOS with a new ROM.. IYou should flash the latest bios from HP's website first and see if it has SLIC 2.1. If it doesnt use a modified BIOS which you can probably find here.
Sorry I used wrong choice of words. Flash.. a BIOS that has SLIC 2.1 I doubt if the HP BIOS will provide SLIC 2.1 in this case. Older machine pre Win 7. I've been looking and the given linked threads have some info.. but its not very clear (I've done several Lenovo & Dell Mod BIOS updates). I'd appreciate if you could guide.
Did it come with XP or vista? If it came with vista and isnt too old a BIOS update might even have SLIC 2.1
I did the above and it did install SLIC 2.1 ok, but now the WAN card has completely vanished. Is there some way to have SLIC 2.1 and the Broadcom WAN card at the same time?