Though it does not change much, you should study RFC5545 as it supersed RFC2445.
to do what you want you need to set a rule which occurs every week, on monday and thursdays at 10 and 14 hours and then select the second and third isntances to only have monday 2pm and thursday 10am.
translated to RRULE this becomes
RRULE:FREQ=WEEKLY;INTERVAL=1;BYDAY=MO,TH;BYHOUR=10,14;BYSETPOS=2,3
the duration is set by the DTSTART and DTEND: just put the first instance of your calendar event and make the DTEND one hour after DTSTART.