Thanks for your comments. I agree with Michael B, what is the point of having these definitions if all they mean is clockwise or anticlockwise (as per definition no.1 from the American Meteorological Society)? We don't call low pressure systems anticylones in the southern hemisphere because they rotate clockwise.
On a totally unrelated note, I have been doing some reading up on hodographs and storm relative helicity, 0-6 km shear etc. Really interesting stuff. I would like to start using hodographs to start pulling out more useful info. The problem is I can't find any programs to plot hodographs. I know there is a program called SHARP but wouldn't have the slightest idea how to get my hands on it.
From what I understand, 0-6 km shear is important for supercells but low-level (say 0-1 or 0-2 km) storm relative helicity (SRH) is important for tornadoes. 0-6 km shear is relatively easy to measure (or estimate), SRH is not. Might be interesting to do some rough calculations of SRH from some Australian events. Using model data (or actual soundings) and modifying low-level winds based on surface observations should be somewhat accurate. Storm speed and direction could be calculated from radar loops.