Add Code Signing Authenticode to VB6 Apps

I have several VB6 apps to which I want to add Code Signing. This should avoid the "Unknown Publisher" warnings. I'm looking for some direction as to purchasing the Certificate, then building some type of batch file to add the required info to my apps. I'm definitely open to your just suggestion of some third party software for doing this also. I need this to run in XP, Vista and Win 7, 32 and 64 bit, and it MUST work on VB6 apps.