I googled it for you:
http://www.mediafire.com/download/nmz771n1gb97ak7/Themehax_Installer_offline_v1.2.zip
Simply replace the existing installer with that one. It's not the 1.3 version though (1.3 lets you select whether to autoboot or not)
What I did was that I installed it over the autoboot version of the normal installer, but kept the "themepayload" directory from the autoboot version, since that contains the autobooting payloads. That worked just fine and I was able to keep autoboot.