.ics file that creates an event on the last working day of every month

BEGIN:VCALENDAR
BEGIN:VEVENT
DTSTART:20100630T093000Z
DTEND:20100630T093000Z
RRULE:FREQ=MONTHLY;BYDAY=MO,TU,WE,TH,FR;BYSETPOS=-1;WKST=SU
SUMMARY:Do something on the last working day of the month
BEGIN:VALARM
TRIGGER:-P1D
ACTION:EMAIL
ATTENDEE:MAILTO:user@domain.tld
SUMMARY:*** REMINDER: Do something! ***
DESCRIPTION:Don't forget to do something - tomorrow is the last working day of the month!
END:VALARM
END:VEVENT
END:VCALENDAR