No prob! You essentially need a program running on the pilot's PC, which sends data to a phpVMS module at regular intervals, the module then parses it and through the API, it will update the map.
So essentially, you're sending XML from the program from the app, to a URL, something like:
phpvms.net/action.php/flightgear_acars/
Then a function in there would take the XML send via POST, and parse it out into a data structure like this:
$data = array(
'pilotid'=>$pilotid,
'code'=>$code,
'flightnum'=>$flightnum,
'depicao'=>$depicao,
'arricao'=>$arricao,
'aircraft'=> $aircraft,
'registration'=>(string) $xml->AircraftTailNumber,
'flighttime'=> $flighttime,
'landingrate'=> (string) $xml->ONVS,
'submitdate'=>'NOW()',
'comment'=> trim((string) $xml->COMMENT),
'fuelused'=> (string) $xml->BlockFuel,
'source'=>'fsfk',
'load'=>$load,
'log'=>$log,
'rawdata'=>$rawdata,
);
$ret = ACARSData::FilePIREP($pilotid, $data);
That code is pulled from FSFK, which sends in XML, and then it files the PIREP. The rest is taken care of behind the scenes.
You can probably use an existing ACARS module in bits and pieces (the data structure and API portions), but you'd have to write the 'fill-ins' to the structures to match the data which is being sent to it. They're all different.