Gmt java Script

Gday All with the help of some of you guys out there in java script land i managed to get my time of day script working. NOw the prolem is that the script works great for system time can anyone tell me how i can edit the following code to read zulu time instead of system time. Also to only show on a specific date.

<script language = ‘JavaScript’ type=”text/JavaScript”>
var time = new Date();
var hours = time.getHours();
var minutes = time.getMinutes();
var lim = (hours*60)+minutes;

if(lim>=(4*60+0) && lim<=(4*60+19)){
document.write(“<IMG SRC=’http://www.westairairlines.com/Cat%20Routes/images/Boarding.gif‘>”);
}
else if(lim>=(4*60+20) && lim<=(4*60+45)){
document.write(“<IMG SRC=’http://www.westairairlines.com/Cat%20Routes/images/nowboarding.gif‘>”);
}
else if(lim>=(4*60+46) && lim<=(5*60+0)){
document.write(“<IMG SRC=’http://www.westairairlines.com/Cat%20Routes/images/Departing.gif‘>”);
}
else if(lim>=(5*60+1) && lim<=(7*60+10)){
document.write(“<IMG SRC=’http://www.westairairlines.com/Cat%20Routes/images/Inflight.gif‘>”);
}
else if(lim>=(7*60+11) && lim<=(7*60+30)){
document.write(“<IMG SRC=’http://www.westairairlines.com/Cat%20Routes/images/Landed.gif‘>”);
}
else
document.write(“<IMG SRC=’http://www.westairairlines.com/Cat%20Routes/images/Closedon.jpg‘>”);
</script>

Thank you in advance

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