How can I change the maxlength in an attrib read only text box?

I'm trying to utilize and attribute set to read only to create a popup link. As much as I despise popups, I must have one here. I've tested links and javascript there, but it maxes at 64 characters and I need more. I can't figure out where to change it. I've used the developers toolbox and even just changed a couple of files hoping for luck, and no luck at all.

Not sure what an attribute has to do with a popup window. Attributes can trigger a javascript event that can open a popup, however you have to use javascript to create a popup or use a link with target="_blank"

Dont understand what the maxes out at 64 character means.

Sorry for the confusion. I created an option name and made it a "read only". Then I created an option value for it and the text box for entering the option value has a "maxlength" of "64" and I need to enter more than 64 characters in it. The popup is really irrelevant. Bottom line, I need the maxlength for the textbox of a read only option value to be longer. How can I modify that? I realize that I will likely be editing a core file outside of the template structure, but I need to do it anyway.

Nevermind.

I gave up waiting on this and decided to do it with jQuery. That keeps the link simple and accessible. http://www.djsipe.com/2008/07/04/doing-pop-ups-the-right-way-with-jquery/

Thanks anyway,
Gary