Alright I touched on Movabletype and SEO this last week in my best movable type plugins article with the intent to come back and provide some specific details. I will tell you that Movabletype is optimized quite well out of the box, but there are a few quick tricks to easily providing the spiders with some dynamic content.
For my main home page and category index pages I hardcode most of my meta data. Your meta tags will be at the top of the template within the <head> tag. You can get fancy on your index pages but I cannot really see why. Optimize these two templates by hand for whatever keywords you are targeting site wide.