I think section 10.3 of the manual describes what you're trying to do. You'll need to attach the inspector to its own display.
Personally, when I have an overabundance of model-level parameters, I prefer to used a TabbedInspector to organize them by category under the "model" tab (see section 10.6.4). I connect each sub-tab to its own inner class inside my global parameters object (I like separating parameters from my SimState, but that's a separate discussion). That way everything is still in one place (both code-wise and GUI-wise), but not as overwhelming.