Exchange Server - SSL certificate expired

Hi,
I have an exchage server 2007 with an expired ssl certificate. For
many reasons I can not renew the certificate. So I have bought a new
one.
Now I am waiting for the CA release a new certificate.
To buy a new certificate I have uninstalled the old one and a make a
new request on IIS. But now OWA has stopped to work.
I cant leave my server offiline so while I wait for the CA issue I
would try  to make a new self signed certicate or reinstall the old
one... Is that possible ? HOW ?
thanks very much for any help.
wiles

In 2007, you need to create a certificate request through the exchange
management shell and enable it through there.

Sorry I dont understand...
to create a self signed certificate I have to create a request by
excchange shell and then enable it ?
But I dont understand what is I have to enable if I havent a
certificate ...
please tell me more...

You have to create a certificate request inside the management shell.
You'll have to create a certificate request first. Create the
certificate, then import it into IIS and then enable it for the
specific services which in this instance is IIS through the management
shell. The self-signed cert is not trusted by your system so you will
have to create one from your internal CA if you have one or get one
through an external third party like verisign.

Follow the guidelines from technet.

http://technet.microsoft.com/en-us/library/bb310781(EXCHG.80).aspx