Free multiplatform oscilloscope with custom oscilloscope support
Many o'scopes have some hardware connected by USB to a standard computer which displays the results using some open-source software.

Perhaps you could tweak some of that open-source software to work with your scope?

If that's too much work, perhaps you could buy an "open hardware" oscilloscope that already works great with that open-source software?

There's a bunch of "open hardware" o'scopes listed at http://opencircuits.com/Oscilloscope .