packaging jruby gems in self contained jar - jar

Question

I'm trying to package compass/sass into a self-contained jar so that I can use compass without installing jruby.
I installed jruby and warbler on a Windows7 machine, running Java 1.6.0_37
I created a folder, named it jrcompass, then installed compass into it, i.e.
jruby -S gem install compass -i .
then I ran in it:
jruby -S warble
which created a file named jrcompass.jar of about ~20MB in size. so far so good.
problem is that when I try to execute the jar I get an error message (below). it seemed from the error that jruby.home was not set, so I passed it as a property in the command line and that worked, but it defeats the purpose of having a self-contained jar.
if I try to pass . as jruby.home then I get an error that it can't find rubygems
any help would be appreciated. TIA.
C:\Apps\test\jrcompass>java -jar jrcompass.jar
Gem::LoadError: Could not find compass (>= 0) amongst [rake-0.9.2.2]
to_specs at jar:file:/C:/Users/Admin/AppData/Local/Temp/jruby9093955264697226808extract/jruby-stdlib-1.7.1.jar!/META-INF/jruby.home/lib/ruby/shared/rubygems/dependency.rb:247
to_spec at jar:file:/C:/Users/Admin/AppData/Local/Temp/jruby9093955264697226808extract/jruby-stdlib-1.7.1.jar!/META-INF/jruby.home/lib/ruby/shared/rubygems/dependency.rb:256
gem at jar:file:/C:/Users/Admin/AppData/Local/Temp/jruby9093955264697226808extract/jruby-stdlib-1.7.1.jar!/META-INF/jruby.home/lib/ruby/shared/rubygems.rb:1231
(root) at file:/C:/Apps/test/jrcompass/jrcompass.jar!/jrcompass/bin/compass:22
load at org/jruby/RubyKernel.java:1046
(root) at file:/C:/Apps/test/jrcompass/jrcompass.jar!/META-INF/main.rb:1
require at org/jruby/RubyKernel.java:1027
(root) at file:/C:/Apps/test/jrcompass/jrcompass.jar!/META-INF/main.rb:1
(root) at jar:file:/C:/Users/Admin/AppData/Local/Temp/jruby9093955264697226808extract/jruby-stdlib-1.7.1.jar!/META-INF/jruby.home/lib/ruby/shared/rubygems/custom_require.rb:1