Well, this is a new one for me. A user said that he had a procedure with approximately 4000 ListBox AddItem lines in it and was getting an error from Visual Basic about the procedure being too long.
I personally didn't remember VB having a limit of the number of lines in a procedure, but this guy found it. The first thing I would suggest is that the data (entered manually) be put into a database. The developer could then query the database and return as many rows as necessary for the application to work.
The point of this is that if you're manually entering more than a few data values, that data should be put in some sort of permanent storage mechanism OUTSIDE of the application. This includes files, databases, XML files, or whatever you want -- just don't put it directly in the application.