This assumes the other services are already installed: Open Registry editor via start -> run -> regedit, and browse to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
Find the corresponding key for the service you want to add dependencies to, it is usually named after the service, but may be abbreviated, so you may have to search for it. When you find the key, click on it in the left hand pane and in the right hand pane you will see its strings and other values, right click on the key and select new -> Multi-string, name it "DependOnService" edit the multi-string, entering each service (using the service key name, not how its listed in services)you want your service to be dependant upon. To see an example, pick a service with existing dependencies, i.e. the Messenger Service and view its DependOnService values in registry editor.