Try running the shaer filter - it has a "12 week % change" criteria. It will pop out shares not sectors, but from that, given that most sectors are owned by few shares, you should be able to get there.
One way is to go to the Indices under Market Data. Do a graph of the Indice sector with an over lay of the all share graph. You will soon enough pick out the top and bottom sectors. You can then overlay the sector graphs on top of each other and work it out the top and bottom sectors that way. Takes a bit of time. You will be dead without ADSL