[news.eclipse.tools.jdt] External tool - running Ant

["John Buntz" <jbuntz@xxxxxxxxxxx>]

I am new to Eclipse and Ant, so bear with me here. I am trying to run an Ant 
script and I want to pass the project workspace to the Ant script.

What do I put in the Arguments:  I tried

mytarget ${project_loc}

When I run the tool I get:
BUILD FAILED: Target `C:\eclipse\workspace\e2_trunk' does not exist in this 
project.

Is the Argument supposed to be in a property name format?