with'ing a "foreign" package or subsystem

[Matthew Heaney <matthew_heaney@acm.org>]

Suppose my company and another company are collaborating on building a
large software system written in Ada.  We each go off and separately
build the subsystems we're responsible for, and then come together some
time later for system integration.

During development, I needed a stack, and I implemented the following
package:

generic
  type Item_Type is private;
package Stacks is ...;

and my company has been using it for a while.

But come integration time, the other company (call them ACME) had also
written package Stacks, but with a different interface, and they're
using their version of Stacks everywhere.

Can both packages coexist in the same application?  Is there a way to
give a package a "virtual" subsystem, to prevent name-space conflicts
like this?  Something like:

package ACME.Stacks renames <ACME company's "Stacks">;

I seem to recall reading something like this in the Ada95 Rationale, but
don't know if any vendor has actually provided such a mechanism.  

In any case, what is the intended mechanism for resolving library-level
name-space conflicts?

Curious,
Matt