Quick update--WePeel's instructions work perfectly to install the Toolkit on El Capitan. Start from scratch, and follow them exactly, they will work. Unfortunately, I'm still having stability/crashing issues with that version. So, I tried to make a Wineskin version that will work on El Capitan. The Wineskin wrapper was surprisingly easy to make, and the Toolkit launches correctly. I can use the Packer/Unpacker to change app IDs, but anytime I try to convert something I get a big Application.ThreadException error. This could be related to Wineskin, but given that these errors appear in the standard Windows version of the tool as well, I'm not quite sure how to troubleshoot it. If anybody has any ideas I can play around with it. If I can get the converter working then of course I'd be happy to post the Wineskin version for anybody who would like to try it.