I am assuming that your Classic ASP page(s) use VBScript for the server-side
code. If this is true, then no, you can't. Because the .NET code is compiled
(you create a .dll file) and Classic ASP code is interpreted (it does not
require a compiler, you just need a web server that supports Classic ASP),
they server-side code cannot be shared between them. However, one thing that
could make it easier to write code that does the same thing for Classic ASP
is to use the same, or a similar, algorithm to write a version for VBScript.
This shouldn't be too hard since many of the basic constructs are the same
in VBScript and VB.NET. But my personal advice would be to simply convert
the Classic ASP page(s) to ASP.NET, it is not a good idea to mix Classic ASP
and ASP.NET. If you would like any help doing any of these things, let me
know, I have worked with Classic ASP, VBScript, ASP.NET, and VB.NET.