sorry, back again - I am trying to use the scripts from dannynygan's site

Supposing I am trying to colour 1 shape two diff colours (top and bottom) i select the bottom faces hit 'assignMaterial' then select the top faces and again hit 'assignMaterial' - it keeps on covering the whole object with the second material!!

if you can understand what I am getting at and have any ideas what I am doing wrong I would be very grateful