Question : Route all mail through smarthost

I have an organization that out of desperation (because of a poorly configured server) switched their MX records to use Google apps mail and they have Google forward all their mail to their exchange server.  Half of the users use google apps mail now and half use outlook / exchange.  When the Outlook / Exchange users send mail to an inside user that only uses google, they never see it, because they never check their exchange accounts.  The Outlook users get mail from google users because google forwards all it's mail to the exchange server.  I tried configuring a smart host but exchange grabs the inter-org mail and doesn't route it through the smarthost.  I'm the new IT guy and have already suggested switching back to exchange, but they are apprehensive due to previous issues.  The only thing I can think of to remedy is to configure a POP3 account in Outlook that uses the gmail smtp server and Exchange pop3. and make it the default account.  That way all new mail will go out through gmail, and when replying they will have to change the outbound account if necessary.
What to you think?

Answer : Route all mail through smarthost

Well i guess the final answer is that it just can't be done.
Thank you for you time.