preparing soill
 

There is a good amount of organic matter in my heavy soil.
How should I prepare the soil for the tomatoes?
I would rather not use compost since the soil already takes up to much space in my greenhouse.
Will dried cow manure suffice?

Well, from what you say it sounds like you're all set. You probably just have to dig some holes and place your seedlings in them. You can add some cow manure (I have sheep and horse manure). Your maters will like it. My soil is not as rich as yours is, so I constantly need to add some organic matter to it. Other than that you just have to fertilize it regularly and pray for good weather.