This article explains how to configure IIS Application Request Routing (ARR) to work with Lync Server 2013 on Windows Server 2008 R2 or Windows Server 2012 and serve as a replacement for TMG and alternative to deploying UAG.
Check it out here:
http://masteringlync.com/2013/02/12/using-iis-application-request-routing-arr-as-a-tmg-replacement/