Applying logic to Validator controls

Here's an interesting one!

I have a RadioButtonList control, containing two ListItems. These two Radio Buttons toggle each other, so that only one is selected at a time. When the second is selected, it affects whether a Textbox is enabled or not, and also erases the text in the Textbox when selected. Lastly, a Button is present to execute the selections made.

I have a RequiredFieldValidator and a RegularExpressionValidator on the Textbox, since when the first Radio Button is selected, I need to validate the entry. However, I need to turn off the functionality of the Validator controls when the second Radio Button is selected.

Any ideas? I'm coding in VB.NET. Thanks in advance!
...