While I'm slightly uncomfortable to mention it, there are applications that can sample a hardware synth. The one I have is Extreme Sample Converter:
http://www.extranslator.com/index.php?page=exsc But it is only 32bit (which isn't that big a deal) and is very old at this point. I've never used it to sample hardware but that is one of the things it was designed to do. I have used it to sample soft synths (which it does, but 32bit only).
To sample hardware you hook the hardware to your audio card and your MIDI to the synth and Extreme Sample Converter plays every note (at multiple velocities) and records the sounds. Then packs that all into one of a several sampler formats. What you end up with is a sampled version of the synth that can use in a modern instrument. (It also can read a bunch of old sampler formats and convert them if that's what you have as well)
I'm pretty sure Image Line has a sampler product that does something like it, but I can't think of the name. And maybe the Chicken Systems translator product can do hardware sampling, I never really looked into it. Google might be your best friend at finding a solution.
The problem with sampling hardware though is you pretty much have to sample every single patch, which can be a lot of data wrangling. And what you end up with is kind of "fixed". To produce something better starts to become real product development work, and there is a reason most sampled libraries are so expensive. But if you only wanted a handful of patches you should be able to work something out without that much difficulty.