although I assume this will also work in all Microsoft Office applications, two links for you to get you started;
http://msdn.microsoft.com/en-us/library/aa223971%28v=office.11%29.aspx - BorderColor Property, and
http://msdn.microsoft.com/en-us/library/aa223974%28v=office.11%29.aspx - BorderStyle Property.
I hope they help.
How can I change the setting of a combobox via vba? I want to change the border style and color. Please assist.