Just registered to help out as I was having problems with Isone.
Turns out I was trying to use the 64bit version as Vincent stated. The Toneboosters plugin download includes 32bit versions (
http://www.toneboosters.com/download/).
I made a new vst folder inside my MusicBee installation (I've got a lot of vsts for my dayjob) and put just the 32bit isone dll along with my registration file for it in there. Once the correct path is set in MB, and after a restart, it shows up in the DSP Effects list. HOWEVER, there are some pretty serious shortcomings:
- no presets
- gui controls don't work
I overcame this by taking a screenshot of the custom preset I use in Reaper and setting parameter values via keyboard input - double click on a number field and enter numerically. This works fine except for the fact that you are unable to do this with the EQ section, which needs direct mouse control over its EQ handles. This is a real pain because I need 1-to-1 match-up with the settings I use inside Reaper for work.
Anyway, this should get you most of the way there. Good luck!