Wildcard commands can be used for that.
Press F1 while VoiceAttack has focus to open VoiceAttackHelp.pdf in your default PDF viewer, which contains information on VoiceAttack's features, and navigate to the "Wildcards" subsection of the "1 - Command Input" subsection of the "Command Screen" section.
Do note that this will rely on the dictation capabilities of the speech recognition system, and as such accuracy will be lower than with predefined phrases, as is also hinted at in the documentation.
You'll want to make sure your speech recognition profile is well-trained (at least three times is the recommended absolute minimum). Instructions for starting additional training can be found
here.