This is not possible at the moment. A
feature request was made to see if it would be feasible to implement.
However, you can use dynamic command sections(VoiceAttackHelp.pdf page 16 and 17) to achieve the same goal.
E.G.
select radio channnel [0..9]Press R key and hold for 0,06 seconds and release
Begin Text Compare : [{TXTNUM:"{CMD}"}] Equals '0'
Press NumPad 0 key and hold for 0,06 seconds and release
Else If Text Compare : [{TXTNUM:"{CMD}"}] Equals '1'
Press NumPad 1 key and hold for 0,06 seconds and release
Else If Text Compare : [{TXTNUM:"{CMD}"}] Equals '2'
Press NumPad 2 key and hold for 0,06 seconds and release
Else If Text Compare : [{TXTNUM:"{CMD}"}] Equals '3'
Press NumPad 3 key and hold for 0,06 seconds and release
Else If Text Compare : [{TXTNUM:"{CMD}"}] Equals '4'
Press NumPad 4 key and hold for 0,06 seconds and release
Else If Text Compare : [{TXTNUM:"{CMD}"}] Equals '5'
Press NumPad 5 key and hold for 0,06 seconds and release
Else If Text Compare : [{TXTNUM:"{CMD}"}] Equals '6'
Press NumPad 6 key and hold for 0,06 seconds and release
Else If Text Compare : [{TXTNUM:"{CMD}"}] Equals '7'
Press NumPad 7 key and hold for 0,06 seconds and release
Else If Text Compare : [{TXTNUM:"{CMD}"}] Equals '8'
Press NumPad 8 key and hold for 0,06 seconds and release
Else If Text Compare : [{TXTNUM:"{CMD}"}] Equals '9'
Press NumPad 9 key and hold for 0,06 seconds and release
End Condition
This will function pretty much like prefix/suffix would; Pressing R is what the prefix would do, pressing a numpad key is equivalent to the suffix.
The "{TXTNUM:}" token(VoiceAttackHelp.pdf page 142) will filter anything that's not a number from your spoken command phrase(represented by the "{CMD}" token), so you can add "TACAN" to the command name anywhere and it'll still work(I.E. you can duplicate the command without setting it up from scratch again).
I should also note that categories are only intended to organize commands for easier maintenance, they do not imply any relation or separation between those commands programmatically(although they can be used for the new "Set/GetSessionEnabledByCategory" methods for inline functions and plugins).