[OS X TeX] PSTricks in Context

[David Arnold]

All,

I have this little file:

\starttext

\usemodule[pstric]

\startPSTRICKS
\pspicture(0,0)(10,10)
\psline(0,0)(10,10)
\endpspicture
\stopPSTRICKS

\stoptext

In Texshop, I try to compile with Context. But I get this result:

http://msemac.redwoods.edu/~darnold/Experiments/context.pdf

Obviously, I need to enable write18 or some such thing. Can folks  
show me how to do this in Texshop on the Mac?

D.