如何为不同的ant任务提供自定义log4j.xml？

I have a build file that as part of the build process relies on several taskdefs. These taskdef items (for example, webdoclet and jasper2) use log4j as a logger. Ideally, I'd like to be able to provide a different log4j configuration file for each, but minimally, I'd like to be able to specify which log4j configuration file is used.I have a build file that as part of the build p