This was not as easy as i first expected but here is my solution:
This block opens the new document with the designated libray as default savelocation:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<body>
<a href="javascript:;" onclick="CoreInvoke('createNewDocumentWithRedirect2', event, 'http://mysite.local/project/TempLib/template.docx', 'http://mysite.local/project/Doclib', 'SharePoint.OpenDocuments', false, 0, true, 0);"><h2 class="ms-rteElement-H2B">New Document</h2></a>
</body>
</html>
Leave the savelocation empty and the user will be promptet to select a location manually i.e. the solution I was looking for initially:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<body>
<a href="javascript:;" onclick="CoreInvoke('createNewDocumentWithRedirect2',event, 'http://mysite.local/project/TempLib/template.docx', '', 'SharePoint.OpenDocuments', false, 0, true, 0);"><h2 class="ms-rteElement-H2B">New Document</h2></a>
</body>
</html>