Using the instructions provided, I setup the plugin locally and point it to my existing installation of NodeJs (since it is a windows machine). I then setup my job to use an execute script to get my node version, which works. When I add a execute nodejs script to my build with this in it:

var sys = require('sys');
sys.puts('build number:' + process.env['BUILD_NUMBER']);
sys.puts('current directory: ' + process.cwd());

I get this error when I run the job:

Building in workspace C:\Program Files (x86)\Jenkins\jobs\NodeJs\workspace
[workspace] $ sh -xe C:\Windows\TEMP\hudson3559847244933178029.sh
+ node --version
v0.10.26
[workspace] $ C:\Windows\TEMP\hudson6840666181877118834.js
%1 is not a valid Win32 application
FATAL: command execution failed
java.io.IOException: Cannot run program "C:\Windows\TEMP\hudson6840666181877118834.js" (in directory "C:\Program Files (x86)\Jenkins\jobs\NodeJs\workspace"): CreateProcess error=193, %1 is not a valid Win32 application
at java.lang.ProcessBuilder.start(Unknown Source)
at hudson.Proc$LocalProc.<init>(Proc.java:244)
at hudson.Proc$LocalProc.<init>(Proc.java:216)
at hudson.Launcher$LocalLauncher.launch(Launcher.java:773)
at jenkins.plugins.nodejs.tools.DecoratedLauncher.launch(DecoratedLauncher.java:49)
at jenkins.plugins.nodejs.tools.NpmPackagesBuildWrapper$2.launch(NpmPackagesBuildWrapper.java:88)
at hudson.Launcher$ProcStarter.start(Launcher.java:353)
at hudson.Launcher$ProcStarter.join(Launcher.java:360)
at jenkins.plugins.nodejs.NodeJsCommandInterpreter.perform(NodeJsCommandInterpreter.java:84)
at jenkins.plugins.nodejs.NodeJsCommandInterpreter.perform(NodeJsCommandInterpreter.java:42)
at hudson.tasks.BuildStepMonitor$1.perform(BuildStepMonitor.java:20)
at hudson.model.AbstractBuild$AbstractBuildExecution.perform(AbstractBuild.java:784)
at hudson.model.Build$BuildExecution.build(Build.java:199)
at hudson.model.Build$BuildExecution.doRun(Build.java:160)
at hudson.model.AbstractBuild$AbstractBuildExecution.run(AbstractBuild.java:565)
at hudson.model.Run.execute(Run.java:1670)
at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:46)
at hudson.model.ResourceController.execute(ResourceController.java:88)
at hudson.model.Executor.run(Executor.java:231)
Caused by: java.io.IOException: CreateProcess error=193, %1 is not a valid Win32 application
at java.lang.ProcessImpl.create(Native Method)
at java.lang.ProcessImpl.<init>(Unknown Source)
at java.lang.ProcessImpl.start(Unknown Source)
... 19 more
Build step 'Execute NodeJS script' marked build as failure
Finished: FAILURE