CallByName does some kind-of that you want (but not true macro-substitution)
See my posting to Thread #601410

In addition see the following MSDN topics:

HOWTO: Use the CallByName Function to Run a Procedure (Q186143)
http://support.microsoft.com/default.aspx?scid=kb;EN-US;q186143

Calling a Property or Method Using a String Name
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vbcon98/html/vbconcallingpropertyormethodusingstringname.asp

HTH