[kh99]

Well, it looks like rep power is calculated by starting with 1 and adding on to it for # of posts, days registerd, and reputation. So if you wanted to start with 10 instead of 1 you could make a plugin using hook reputation_power and this:

if ($reppower != 0) 
   $reppower += 9;

The check for 0 is because $reppower is set to 0 in certain cases (like they haven't met the minimum # of posts yet).

As for setting it for people already on your board, they're still going to have theirs calculated as mentioned above, they'll just get 9 more on top of that. I'm not sure if that's what you want to do, especially if you allow negative reputation.