I've found XTend and it really sounds great! But, I can't see any standalone command line compiler for this language. It seems only to run under eclipse. I've done some research, and found some people saying, that it has a command line compiler, but I can't find a download link.
Does the compiler exist, standalone, or do you need eclipse to use it?
It is not documented, but there is indeed a command line compiler in the Xtend code base - the same one used by the Maven plug-in (that is documented in the Xtend homepage).
If Maven plug-in does not work for you, then you could download the standalone jar version directly from the Maven repository at http://build.eclipse.org/common/xtend/maven/org/eclipse/xtend/org.eclipse.xtend.standalone/2.3.1/ (for version 2.3.1), and execute the org.eclipse.xtend.core.compiler.batch.Main class from it.
This class executes the xtend compiler, and usage information can be displayed (also readable from the source file).