If your machine is Intel based, you might be able to use the Windows version via boot camp. As I understand it, the developers are pretty clear they are not going to try to support operating systems that are no longer supported by the manufacturer. This is a part time project for the main developer who does this after a day job on payment processing systems, ably abetted by a couple of UK gents.
You might ask in a Mac forum elsewhere how you compile programs for the Mac. Compiling programs can be a little tricky, so they might be able to help you get through a little better there. BUT you are likely to be on your own if it doesn't work.