have you tried using getURL("javascript:") instead.
I believe the ActiveX control does support the javascript interface, but not sure how you would set up fscommands through js other than the way the plug-in supports it.
Code:
// Javascript to enable fscommand for plug-in
function fs_evalFSCommand(cmd,args){
// if comamnd contains complete function string ignore args
// otherwise build a function call with open and closed parenthesis
if(cmd.indexOf('(') != -1 && cmd.indexOf(')') != -1){
var commandstr = String(cmd);
} else {
var commandstr = cmd + '(' + args + ')';
}
// eval function call
eval(commandstr);
}
window[playerID + '_DoFSCommand'] = fs_evalFSCommand;