PHP can parse xml and you can make a calendar using PHP, as I have done both.
The solution is more in depth than a simple post. I would recomend just doing a search for a tutorials on how to parse xml using PHP (also look up parsing RSS feeds using PHP). Once you know how to make the data into PHP variables you can then take any one of hundreds of PHP calendar scripts or tutorials and make your calendar.
And if you have a problems or question on how to manipulate particular parts of the code I am sure you can get more help here.
