If somebody from PC called me I would be scared as to how they got my number XD
I don't have an MSN either. Well, I do, but there are like only a couple of people on it from when I was learning to make a Pokémon game for the Game Development forum, and seeing I'm not doing that anymore I don't really go on (damn it Eliminator! Be more social!).
I guess that only leaves PM or VM, and I'm not aware of anyone being offered a position as a moderator through VM. Honestly I wouldn't care how I was contacted, but really, there only is one way to contact me.
As for whether I'd accept or not, I most likely would. The only things that would persuade me to decline would be if the position was in a forum I had no clue about (like.. the Emulation forum or something) or if there were far better candidates for the job (I can think of a tonne of people who would be more suitable to mod the Fan Fiction section than myself).
For forums I'm more familiar with, if I felt someone else was better for the job, I wouldn't decline the position straight away but I'd mention my concern that someone may have been overlooked. If the higher staff have come to the conclusion that I'm the best candidate for the job then I'm not complaining, but if there is someone more deserving of a position I'd hate to take it from them.