Right now it's possible to configure the xvnc plugin in the jenkins configuration but it doesn't seem possible to do so when using the plugin in a pipeline script (all you can configure is takeScreenshot and authority).

See https://github.com/jenkinsci/xvnc-plugin/blob/master/src/main/java/hudson/plugins/xvnc/Xvnc.java#L93

It would be nice to be able to control the command line when using it, with something like:

wrap([$class: 'Xvnc', cmd = 'vncserver :$DISPLAY_NUMBER -nolisten tcp -geometry 1280x1024']) {
...
}