I found the URLs! I'm putting them out here in case anyone else needs them.
URL to use for a Promoted Link Tile in sharepoint 2013 (put your URL in any where it says MyURL without brackets):
{MyURL}/_layouts/FormServer.aspx?XsnLocation={MyURL...template.xsn}&ClientInstalled=true&Source={MyURL}&DefaultOpen=0
URL to use for a link within a CEWP:
<a href="BLOCKED SCRIPTcreateNewDocumentWithProgID(escapeProperlyCore('{MyURL}/Forms/template.xsn', true), '{MyURL}/', 'SharePoint.OpenXMLDocuments', true)">Click Here to Open a New Form</a>
(I see it is blocking script... the BLOCKEDSCRIPT characters are: quotes javascript colon i.e. " + javascript + : without the plus signs.)