Arguments For Custom Controls?

I've created custom buttons in a .dll and they work fine, so I thought I'd have a go at creating my own sort of listbox to replace the standard one in my applications. It's basically a panel with a few labels and a button (eliminating the need to select an item in standard listbox then click a seperate button). I want to add these panels to a panel on a form, at run-time, based on rows in a db.

If I try adding any arguments in the New() section of the class file it won't let me use the panel in my toolbox. Is there a way to pass arguments to custom controls, I need a new custom panel for each row in a db so need to pass an id to it to specify records; or even load the records in my application and create a new panel for each record, using info passed to it to fill in the labels on it. Or can I create the panel at run-time and refer to labels within the custom controls, setting their .text properties that way?