how best to track on network ?
registration = XH558
Not necessarily - GAS has the Vulcan in its database as G-VLCN (which is correct as this is it's current registration), so if your database is autopopulated by GAS rather than manually edited to have XH558 as the registration, then looking for XH558 in the list or by setting an Alert isn't going to work.
If you use the Hex code 40109F then you can't go wrong, as this will show even if you don't have the Vulcan's data in your NavData.db3 database.
It's worth looking in MyLog to see if you already have 40109F as you might have picked up the Vulcan without realising it :-)
And of course, the Vulcan will only show up in MyFlights, not via the Network, as it doesn't transmit position information :-(