Similar to localizing a task, you can localize the display name and description of a custom connection manager by setting the LocalizationType property of the DtsConnection attribute. SSIS will look for two properties on the class:
These must be public, static string properties on your LocalizationType class.
The code looks like this:
[DtsConnection(ConnectionType = "MYCONNECTION", LocalizationType = typeof(Strings))]
public class MyConnectionManager : ConnectionManagerBase