Viaual Basic has no direct way of doing that. You have to use Win 32 API calls to do that.
If you want to just show the International Control Panel, do the following Shell "Control.exe intl.cpl" To set the format settings for the OS without having user intervention, you probably have to use CPIApplet API with the CPLINFO and NEWCPLINFO structures. This involves moderate to advanced knowledge of the C programming language, and also requires moderate to advanced experienced in working with the Windows APIs.
But you can declare these functions in Visual Basic as well as the structures and you should be able to do what you desire using VB6. You have asked a difficult question.