Adding additional font sizes?

Is it possible to add additional font sizes or modifY the existing ones in the javascript?

I have taken a look through the javascript files and i cannot see anything that defines the Font sizes, the only thing that seemed to come remotely close was in the fckconfig.js file which has something in the toolbar setups but that doesen't seem to do much except change the names in the drop down list.

If somone could tell me which file actually defines the sizes themselves i could probably edit them myself.

The problem i have is that the fonts are either slightly too big or slightly too small to match the sites static pages i am building the editor into.

Thanks in advance for any answers on this one =)