As you probably knew, or do now since you are searching for this information, Exchange 2007 requires a UCC Multi-Domain SSL Certificate to properly function.  Here are some tips for setting it up.

-Pick your favorite vendor to purchase the UCC SSL from and make the purchase

-Generate the request from the Exchange 2007 Server.  To do this, open the Management Shell and issue the New-ExchangeCertificate command.  A great tool is provided here: https://www.digicert.com/easy-csr/exchange2007.htm.  You can use this tool to generate the request and it will save the information to a file in the path you can specify or leave default

   For Example:  Lets say we have an Exchange 2007 Server whos Internet Address is mail.rockabilly.com and its local domain address is exch07.rockabilly.local.  I would also include remote.rockabilly.com, rockaserver.rockabilly.local, autodiscover.rockabilly.com, autodiscover.rockabilly.local in the list of requested names.  Feeding this into the tool yields the following request:  "New-ExchangeCertificate -GenerateRequest -Path c:\mail_rockabilly_com.csr -KeySize 2048 -SubjectName "c=US, s=Utah, l=YourTown, o=RockABillyDoodles, ou=IT, cn=mail.rockabilly.com" -DomainName remote.rockabilly.com, pcrserver.rockabilly.local, autodiscover.rockabilly.com, autodiscover.rockabilly.local -PrivateKeyExportable $True"  Copy and paste this request into your Exchange Server Management Shell and it will spit out the request to c:\mail_rockabilly_com.csr.  Open this in Notepad and copy and paste the request into the request fields at the site where you purchased the SSL cert. 

-Once the request is received by the registering entity, an email will be generated to approve this request.  The email will go to the contacts on the WHOIS record for the domain.  Ensure you have access to those email accounts so you can approve the request.

-Once the request is approved and you are able to download the certificate, the next step is to install it into the Exchange 2007 server.