I assume that you are looking to create a design-time experience similar to
the full framework or compact framework TabControl... If I'm understanding
you correctly, this will require custom Designers and will be pretty
involved to implement properly. I'll pass along a few article links that
should help you understand the custom design process a little better. Note
that none of these articles will guide you through the process step-by-step,
but they should arm you with enough information to get you going in the
right direction. There is a lot of information that will overlap between
these links, but it just helps to reinforce the basics.
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dndotnet/html/c
ustdsgnrdotnet.asp
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dndotnet/html/c
ustcodegen.asp
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dndotnet/html/p
dc_vsdescmp.asp
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dndotnet/html/v
snetpropbrow.asp
http://msdn.microsoft.com/msdnmag/issues/03/04/Design-TimeControls/default.aspx
http://msdn.microsoft.com/msdnmag/issues/03/05/Design-TimeControls/default.aspx
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpguide/html/cp
conenhancingdesign-timesupport.asp

In addition, since your design-time control is really a full framework
assembly, here are a few newsgroups that you may want to google search for
some additional information.
microsoft.public.dotnet.framework.windowsforms.controls
microsoft.public.dotnet.framework.windowsforms.designtime