I will leave here my two macros to do exactly what I was looking for (big thanks to Spyndel and Marcus):
To toggle just the LINES visibility on PolyFrame:
//ZBrush macro - save to ZBrush 2019.1\ZStartup\Macros\Misc\ folder
[IButton,???,"Toggle PF Line",
[IShowActions,0]
[IConfig,2019]
[IPress,Transform: Pf]
[Loop,1,
[If,([IModGet,Transform: Pf]==0), // if Nothing
[IModSet,Transform: Pf,1] // apply just Line
[LoopExit]
]
[If,([IModGet,Transform: Pf]==1), // if just Line
[IModSet,Transform: Pf,0] // apply Nothing
[LoopExit]
]
[If,([IModGet,Transform: Pf]==2), // if just Fill
[IModSet,Transform: Pf,3] // apply Line & Fill
[LoopExit]
]
[If,([IModGet,Transform: Pf]==3), // if Line & Fill
[IModSet,Transform: Pf,2] // apply just Fill
[LoopExit]
]
]
,,0.5] // half palette width button
To toggle just the FILL visibility on PolyFrame:
//ZBrush macro - save to ZBrush 2019.1\ZStartup\Macros\Misc\ folder
[IButton,???,"Toggle PF Fill",
[IShowActions,0]
[IConfig,2019]
[IPress,Transform: Pf]
[Loop,1,
[If,([IModGet,Transform: Pf]==0), // if Nothing
[IModSet,Transform: Pf,2] // apply just Fill
[LoopExit]
]
[If,([IModGet,Transform: Pf]==1), // if just Line
[IModSet,Transform: Pf,3] // apply Line & Fill
[LoopExit]
]
[If,([IModGet,Transform: Pf]==2), // if just Fill
[IModSet,Transform: Pf,0] // apply Nothing
[LoopExit]
]
[If,([IModGet,Transform: Pf]==3), // if Line & Fill
[IModSet,Transform: Pf,1] // apply just Line
[LoopExit]
]
]
,,0.5] // half palette width button