How do I add a Super Clone button for a community or partner portal site?

The custom button can be created with the global variable $Site.Prefix. This will return the path of the current community.

/* Super Clone */
{!URLFOR($Site.Prefix + '/apex/dh_superclone__superclone?rid=' + MyObject__c.Id + '&cfg=MyConfig')}

/* Super Clone Pro */
{!URLFOR($Site.Prefix + '/apex/lcrm-scp__scpclone?rid=' + MyObject__c.Id + '&cfg=MyConfig')}