Just to follow up....
I spoke with two coworkers. Both seem to agree with what I said here. However, one seems to think Yahoo! charges any time you have a domain outside, but use their nameservers for advanced DNS records.
One coworker has emailed Yahoo! about this to get the exact process, and is hoping for specific instructions which we could then email to you.
At this point, I believe, if you wanted to poke around in your Yahoo! control panel, you should be able to find the place where you enter the CNAME record you need.
Now, I just double checked, and your
www.safeandcozypets.com is using Yahoo! Nameservers. So, this is absolutely where you need to put in yuor CNAME record. It should point to stores.yahoo.net. There is no question about this part.
The only remaining questions are, exactly where this functionality is in your control panel on your Yahoo! account, and whether or not they charge for the ability to point your outside domain to your Yahoo! store. As I said, I am working to get more detailed information for you.
Listen, I am sorry it's making you crazy, as you said, trying to get this done. I can definately understand that, considering you have been at this for months now. Rest assured, I am trying to get the exact information you need.
Let me know if this is helping so far, or if there are any other questions we can answer here. I am interested in getting you up and running, number one, and also in having this information so we can make it available for everyone else as well.