Add configuration options to grape for http proxy settings

Perhaps this already exists, but it would be extremely useful to have a central configuration file or environment variable setting that could be used to store system wide http proxy settings to be used by Grape. Grape uses Ivy internally, but the usual ANT_OPTS approach doesn't seem to get picked up. Using brute force on the command line, I was able to force the proxy settings via:

groovy -Dhttp.proxyHost=<host> -Dhttp.proxyPort=<port> myGroovyScriptWithGrapeGrabs.groovy

However, it appears that the same parameters don't work if you run grape from the command line. For example:

grape -Dhttp.proxyHost=<host> -Dhttp.proxyPort=<port> commons-lang commons-lang 2.4

And if this feature does already exist, or when it is implemented, it would obviously be something very useful to add to the documentation page:
http://groovy.codehaus.org/Grape