Inner Space build 5404 adds support for different "Key Sets" on natively supported Input Devices. As of this post, this is currently the development build of Inner Space but should be pushed live within a couple days. To try the dev build, right click IS and select Patcher, check "Download development (test) patches" then close and restart Inner Space.
Once you're on IS build 5404 or later, ISBoxer 38.2.401.2 is available now and includes an
Inner Space Input Device Editor window for editing Key Sets, and a new
Input Device Key Set Action for switching Key Sets. See
http://isboxer.com/wiki/ISBoxer_Releases for info on how to update manually (this update will likely be pushed this weekend or next week sometime; pushed updates give an update notice when you launch ISBoxer).
So.. in a nutshell, here's what you would do to duplicate the Logitech feature set:
Use the Input Device Editor to add additional Key Sets, e.g. named M2 and M3. You could also add M1, but there is a "default" key set and you can pretend that's M1. The default naming scheme, for your G510, would then add keys named "G510-G1#M1" and so on, available for use in any ISBoxer
Hotkey box. Or if you prefer, you can make G19-G36, and so on (though the hash tag method should be a little easier to use, considering the real name of the button is still in there!). But, generally you would add just the G-keys, not the M-keys, to the Key Set. That will mean the M-keys retain the same behavior (and names) regardless of which Key Set is active.
Once the Key Sets are set up, use an Input Device Key Set Action in a
Mapped Key to adjust which is active. For example, assign M1 to activate the default or M1 Key set, M2 to activate the M2 key set, and so on. The
Light Action will indeed only work on the G11 and G15 models (i.e. not the G510, G13, etc), but I will expand that capability soon as well. So unfortunately you don't get the pretty lights yet on the G510, but you can use sounds, popup text, or even images on Click Bar buttons to help you track the states.
And you can have as many Key Sets as you want, activated on a per-window basis (as determined by the Target of the Key Set Action) by whichever combination of buttons you prefer
I can provide further details on whatever is necessary, but hopefully the documentation is sufficient. Let me know!