[SalesForce] Setup CNAME to force.com site

Try one or more of the following:

Set the debug level to be less verbose (dev console). You'll get major errors back rather than each loop iteration showing up.

There are visualforce global parameters for page and exception. I placed these in a google analytics event on the page so I can see what's being thrown.

Wrap the whole page in a try/catch block, and do a system.debug(logginglevel.error, e) in the last catch. <==assuming you name all your exceptions e like I do). If the log verbosity is the main problem, combine this with #1.

If the error happens after the page loads, like on a save or other action, you could do #3 but use an apex message option to show the error that you're catching on the page (avoid the logs entirely).

Here's the GA script we use (prerequisite is that you have the GA async tag already on the page AND you have your GA id on the salesforce site config page).

<script type="text/javascript">
    var _gaq = _gaq || [];              
    _gaq.push(['_setAccount', '{!$Site.AnalyticsTrackingCode}']);
    _gaq.push([
       '_trackEvent', 
       'Page Errors', 
       '{!$Site.ErrorMessage}', 
       '{!$Site.OriginalUrl}--{!$Site.ErrorDescription} experienced by {!$User.id}']);                      
 </script>

Best of luck!

EDIT

The answer to this question has changed with the SU14 release. See Configure a Custom Domain for Your Community which provides instructions that primarily involve contacting SF Support and the caveats highlighted below.

• To enable HTTPS custom domains for your organization: contact salesforce.com.

• To associate certificates with a domain: contact salesforce.com.

From Setup, click Domain Management | Custom URLs. Before you switch the CNAME of your domain name to point to a new target name, ensure that the new target name exists in the DNS by using dig or nslookup. When you created your domain names affects the target of your CNAME:

• Domain names that were added before Summer ‘13, typically need to have their CNAME adjusted to point to the fully qualified domain followed by .live.siteforce.com instead of to the organization’s force.com sub-domain. For example, if your pre-Summer ‘13 domain is www.example.com, then the target of its CNAME will need to be www.example.com.live.siteforce.com instead of example.force.com before HTTPS will work.
• Domain names that were added in or before Summer ‘13, don’t have the 18-character organization ID in the CNAME target.
• Domain names that were added in or after Summer ‘13, already point to the proper place for setting up HTTPS in a custom domain.
• Domain names that were added in or after Winter ‘14, use a CNAME that points to the fully qualified domain followed by your organization’s 18-character ID and .live.siteforce.com. For example, if your domain name is www.example.com and your 18-character organization ID is 00dxx0000001ggxeay, then the target of its CNAME will need to be www.example.com.00dxx0000001ggxeay.live.siteforce.com.

Original Answer

Bunyan, take a look at the Sites FAQ which says the following:

Q: Does it support HTTPS custom URLs (not force.com URLs) with our own certificate?

A: Not at this time

and

Q: Can i specify my own SSL certificate if i use a CNAME to brand my URL

A: SSL certificates specify an IP address and at the current time we do not provide a feature to host SSL certificates for sites other than the default domain force.com.

From the above, unless something has changed, I'd conclude that at this time it's not possible to do what you desire.