[OS X TeX] Interactive asymptote?

[Vic Norton]

How does one get asymptote to work interactively? Here is what I get from the version that came with MacTeX-2010.

### in terminal ###
Documents$ asy
Welcome to Asymptote version 2.02 (to view the manual, type help)
> draw((0,0)--(100,100));
> Cannot execute gv
Please put in a file config.asy: 

import settings;
psviewer="LOCATION";

where LOCATION specifies the location of your PostScript viewer.

Alternatively, set the environment variable ASYMPTOTE_PSVIEWER
or use the command line option -psviewer="LOCATION". For further details, see
http://asymptote.sourceforge.net/doc/Configuring.html
http://asymptote.sourceforge.net/doc/Search-paths.html
### end of terminal output ###

What should "LOCATION" be for the MacTeX-2010 installation?