Is it currently possible to execute the VJET Java2Js compiler from Maven or it's strongly bonded to the Eclipse IDE plugin?
No it's not strongly bonded to Eclipse plugin and yes it is possible to make this run with a build system such as maven.
It can be run with a java main or ant plugin. There is currently no support for a maven plugin today. We can make this work better by adding these to maven repo rather than just a p2 repo. Something I was planning on doing.
Here is the location of the ant plugin code http://git.eclipse.org/c/vjet/org.eclipse.vjet.core.git/tree/runtime/org.eclipse.vjet.rt.active.javatojs/src/org/eclipse/vjet/dsf/javatojs/prebuild/J2JsBuildTask.java
Here is the location of the java main: http://git.eclipse.org/c/vjet/org.eclipse.vjet.core.git/tree/runtime/org.eclipse.vjet.rt.active.javatojs/src/org/eclipse/vjet/dsf/javatojs/cli/Java2Vjo.java