There's a Two Week Timetable switch on /HAP/setup.aspx under the Booking System tab.
To import the data from SIMS, you'll need to first import the SIMS report and run it. (I also had to edit the report in Design report to filter it by our IT rooms to get any data out of it.) In the resulting XML file, you should be able to see which format your two week timetable periods are in. (We used to be on a two-week timetable, but are not any longer. Ours were in the format 2Wed:1, where 2 was the week number and 1 the period.)
I found that the Lessons as configured in /HAP/setup.aspx under Booking System needed to have a space between P and the period number for the import to match to the right day and period. For example: P 1, P 2.
With this all set up, you can copy the XML file from the SIMS report into App_Data, name it sims-bookings.xmland press the Import SIMS button on /hap/bookingsystem/Admin/, Static Bookings tab. HAP seems to magically know the format of the 2Wed:1 style strings and assign the lessons to the correct week and period for that room.
It's been a while since I did this, and we now are no longer on a 2-week timetable, but it did work for us for several years once we understood the process!