importing a non-standard class file

[Andrew W. Bingham]

Hello - 

I note in the archive that someone has already asked a similar question but
unfortunately there was no follow-up.  Maybe this time...

How can I import a non-standard *.cls file into Layout->Document->Class?
Specifically I would like to use IEEEtran.cls to set the layout of my paper.

Thanks,

Andy Bingham.