Is it possible to run warbler using jruby-complete.jar instead of the full jruby install?

From the command line this works fine: c:\jruby\jruby-1.4.0\bin\jruby -S rake war

However, when I run this I get the error below java -jar c:\projects\History\build\jruby-complete-1.4.0.jar -S rake war

cp C:/projects/X/SVNROOT/jruby/specifications/activesupport-2.3.5.gemspec tmp/war/WEB-INF/gems/specifications/activesupport-2.3.5.gemspec rake aborted! Cannot load gem at [file:/C:/projects/X/build/jruby-complete-1.4.0.jar!/META-INF/jruby.home/lib/ruby/gems/1.8/cache/activesupport-2.3.5.gem] in C:/projects/X/SVNROOT/src/rails/App

I also see this message once in a while:

cp C:/projects/X/SVNROOT/jruby/specifications/rake-0.8.7.gemspec tmp/war/WEB-INF/gems/specifications/rake-0.8.7.gemspec rake aborted! Illegal seek - Illegal seek

Any ideas?

The reason I want to do it with the jar is because I want to build from an Ant task without having the full install of Jruby in place.

Thanks in advance!