The portfile looks good. I have one suggestion: Can you rewrite the part
system "cd ${javadir}/${name}/bin \
&& echo \"java -jar ${prefix}/share/java/${name}/js.jar\" > ${destroot}${prefix}/bin/rhino \
&& chmod +x ${destroot}${prefix}/bin/rhino"
such that it does not use system commands?
See here: http://wiki.tcl.tk/367 . Alternatively you could add the rhino file to the files folder and simply copy it over during installation.
