It is possible to run some apps in "32-bit mode" still (on some machines) in El Capitan. If I wanted to use old 32-bit plugins with Amadeus Pro, for example, I can set AP to open in 32-bit mode.
This isn't recommended and will probably be disallowed in the next OS X release or so, of course, so the real solution is to get a 64-bit driver from the developer. But in the meantime, perhaps something like the "32-bit mode" I suggested might work for you, depending on the files used to provide support.