How to install M_map to matlab

Hi All, I was trying to plot Latitude vs Longitude plot and I came across the M_map, a mapping package, to do that. I tried to install and unpack the directories in matlab/toolbox/local/pathdef.m but it didn't work.

the directions are "you may want to install M_Map as a toolbox accessible to all users. To do this, unpack the files into $MATLAB/toolbox/m_map, add that directory to the list defined in $MATLAB/toolbox/local/pathdef.m, and update the cache file using" rehash toolboxcache.

Can anyone plese tell to do it exactly. Your help will be greatly appreciated. Thanx in advance.