Is it me or is there no easy way to manage large hex numbers, particularly MAC and WWN addresses in Excel?

As I'm feeling lazy, I need to manage a large number of network MAC addresses and FC WWN addresses using minimal work. Particularly, I'd like to have a formula so that when I enter the MAC or WWN of a dual port network/FC card, the 2nd port's address is automatically filled in. It's always a fixed offset of one or two.

Of course, if life were in base 10, everything would be easy, but as we're talking hex, it's a little tricker. There are the excel functions of hex2dec and dec2hex, so that could have been a solution, but it's limited to 10 digits / 40 bits which means MACs and WWNs are out of scope

I've done a quick trawl on the net and there does appear to be a suggestion or two involving VB which I suppose is inevitable, but it's a bit beyond my abilities

Alternatively, is anyone aware of a freeware program that allows us to do this kind of stuff and then import / export into Excel?

Thanks