Template Changes:

Replace:

<?php get_calendar(); ?>

with:

<?php get_event_calendar(X); ?>

...where X is the numeric ID of your event category.

If you want i18n standard weeks (that start on Monday) use:

<?php get_event_calendar(X,'mon'); ?>

You can show the next month as well as the current month. This is really useful for looking forward to upcoming events:

<?php get_event_calendar(X,'sun',2); ?>

You can just show events, and ignore normal posts:

<?php get_event_calendar(X,'sun',1,False); ?>

You can also use three-letter acronyms for day-column headers:

<?php get_event_calendar(X,'sun',1,True,3); ?>

Stylesheet changes:

Id #wp-calendar is no longer a table, but a div that contains one or more tables. At the very least, you'll want to change the selector for the #wp-calendar rule from:

#wp-calendar {

to:

#wp-calendar table {

Add a rule to highlight event days. There is a new class 'eventday':

#wp-calendar a.eventday { color:#a00 }

ADVANCED

If you want to make sure that the ONLY visible future posts are from your event category, then edit the file eventcalendar2.php: Set the value of $event_calendar_category to the numeric ID of your event category. If you don't do this, then all future posts will be visible, not just events.