Hi Svein Thomas,
Thank you for writing.
It seems you will need a custom column with a custom cell. You can see what you can achieve with a custom cell by going to this article in our product documentation - RadGridView - Custom cell. Also, you might want to extend the behavior of the editor. You can do that by creating your own editor which would be specific to your custom column. You can take a look at this help article on Using custom editors.
I hope this will help you. If you need further assistance I would be glad to provide it.
All the best,
the Telerik team
Q2’11 SP1 of RadControls for WinForms is available for download (see what's new); also available is the Q3'11 Roadmap for Telerik Windows Forms controls.