You could bring it into a brian, trough arturos modbus board with analog inputs, and then through a brain, BUT, the jog speed overide at least at the application scale is a global for all six axis, thus you couldnt move X at 40% and Y at 60% at the same time.
I am working on a 6 axis plugin right now in that you can jog all six axis at once, I have one Analog Jog speed overide input, but if you tell me how many you need (i.e. Six?), I could add them to the plug in dialog. Since in a plug in you can talk to the axis perameters individually, you could have different jog speeds I think.
When I get closer to done, with it, I will test with Aurtors boards to see if each axis can indeed do independant speeds........it should be do-able since jog speed is a independant variable for each axis.
THEN AGAIN.........What Brett said may be easier on you, if that key grabber can some how have 2 or more axis jogging at different rates of speed.
scott