use update-rc.d to change runleevels, in a similar way to chkconfig on centos
eg;
sudo update-rc.d nxserver disable
this removes all symlinks from /etc/rc2.d/S* and renames them to /etc/rc2.d/K* which means they used to be Start to Kill
do the same with ‘enable’ to reenable them. or use the ‘defaults’ option