You could navigate the menus using the keyboard to achieve the same thing, E.G.
Press Left Alt+B keys and hold for 0,06 seconds and release
Start Loop : Repeat 5 Times
Press Down key and hold for 0,01 seconds and release
End Loop
Press Menu key and hold for 0,01 seconds and release
Press Down key and hold for 0,01 seconds and release
Press Enter key and hold for 0,01 seconds and release
You might want to consider wrapping that in
Fully restrict mouse movement
Unrestrict mouse movement
so you don't accidentally move the mouse while it's running and select something else.
Otherwise you'd have to use something like
Run application 'firefox' -with parameters '-new-tab "VoiceAttack.com"'
Run application 'firefox' -with parameters '-new-tab "forum.VoiceAttack.com"'
But then you'd need to modify the command to stay in sync with your bookmarks. It doesn't seem to open in private browsing windows either.