1) Click on the link to the self-extracting exe file at University College London: http://www.phon.ucl.ac.uk/home/wells/IPASAMFonts.exe.
2) When prompted 'Would you like to open the file or save it to your computer?', choose 'Open'.
3) Choose 'Next'.
4) Choose 'I accept the agreement' and then 'Next'.
5) Choose 'Install'.
6) Choose 'Finish'.
The installation process is complete. Instructions are available on using the fonts, and further details are available at http://www.phon.ucl.ac.uk/home/wells/fonts.htm.