Multiple bin-directories with virtual directories?

[Guest]

Hi all,
I've got a deployment issue I hope is solvable at all, and appreciate all
help anyone can give me.

We've got an ASP.NET-application (a sort of function library shared by our
customers, a helpApp) that is distributed to several IIS-servers and in
several versions on these servers. The application is a virtual directory in
the site and has the same virtual name regardless of version and exists in
several sites and on several servers. The thing is that it can't be an
isolated application because the root application of the site must be able to
use the functions of our helpApp and vice versa and share session-data.

What we don't want to do is to distribute the helpApps dlls to every sites
/bin/ but instead to the virtual directory helpApp/bin/ and make these
available to the site-application.
This is because there are several versions of the helpApp and lots of sites
on lots of servers using different versions.

Example what we wish for in IIS-configuration:
www.customer_1.com (c:\inetpub\www.customer_1.com)
|- bin (containing site-dlls)
|- helpApp (virtual directory, not application,
c:\inetpub\helpApp\helpApp_v1.1)
|-bin (containing helpApp-dlls)

www.customer_2.com (c:\inetpub\www.customer_2.com)
|- bin (containing site-dlls)
|- helpApp (virtual directory, not application,
c:\inetpub\helpApp\helpApp_v1.1)
|-bin (containing helpApp-dlls)

www.customer_3.com (c:\inetpub\www.customer_3.com)
|- bin (containing site-dlls)
|- helpApp (virtual directory, not application,
c:\inetpub\helpApp\helpApp_v1.0)
|-bin (containing helpApp-dlls)

Is this in any way possible to make the site-application searching for DLLs
in multiple virtual bin-directories, or are there alternate methods?

Thanks,
/Lasse