Hey Richard, sorry I saw you post so late.
In regards of mapping keyboard shortcuts you have several ways to map keyboard keys to function first.
Make sure that all functions you want working on your space mouse buttons do have an assigned key stroke combination on your keyboard and are working.
In Rhino you have in the menu bar:

click on “customize” and you have a very powerful menu to customize your tool bars and most importantly keyboard shortcuts for each command you want to use.
For example:
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to get the “top view” command to work with your “top view” button on the space mouse:
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open the command customize menu described above
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type in the search box for the commands (bottom of screen) “top”
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select the command button “Top view” among the filtered commands
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assign a keyboard shortcut for this command in the field “keyboard shortcut” on the right
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open your Spacemouse menu (you find it in System Preferences / 3Dconnexion)
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go to the “buttons” menu
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select the correct button you want to assign “Top view” to
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make sure you assign exactly the IDENTICAL keyboard shortcut you have assigned in the Rhino menu
Now test within Rhino if this button mapping was successful.
This you simply repeat for every single function.
The beauty about the Spacemouse is that you can assign multiple functions to each button by using modifier buttons.
For example did I assign to the Top View button without modifier key the function “Top view” and assigned “Bottom view” by using a modifier key (for example “option”) to also have the bottom view available.
Good luck and take it slow and methodical - it can get confusing when in a rush 
- make sure all your functions do have a working key shortcut in Rhino itself
- assign those same shortcuts within the Spacemouse software
- verify that you mapped the buttons successfully
As a bonus:
you can also assign keyboard shortcuts of menu bar commands through the Mac OS X menu
System Preferences / Keyboard / Shortcuts / App Shortcuts
Simply add Rhino as an app here and you can assign individual shortcuts to Rhino menu items (only items that are spelled out in the menu bar letter by letter - commands that are not spelled out there cannot be assigned as far as I understand).
This way you have two very powerful ways of assigning shortcuts.
Bonus 2:
Make certain, that you have this neat app installed “CheatSheet”.
https://www.mediaatelier.com/CheatSheet/
It is an app that displays ALL available keyboard shortcuts at any given time available with the foremost app in focus by long holding the CMD key (configurable).
This way you have a very fast way of verifying shortcuts and of course finding shortcuts you don’t know off or have forgotten about.
It is a MUST HAVE app for any Mac user in my opinion.