No problem at all. When you log in to your admin account, under the management menu on the left hand side, you will find "Manufacturers about 3rd down. Here you can create new manufacturers, change their display order, make them acitve/inactive. If you click on the name of a manufacturer, you can add a logo, description, and URL.
I've found with X-cart that the question "Where the #$%% do I find that setting?!?" to come up a lot.
you can surf around
www.heritagetoys.com to see how it works w/multiple manufacuturers.