you could include the script in the boot sequence, wich will start it automaticly on boot
depends on the init style how this is done... for slackware style boot (don't know official name): edit the /etc/rc.d/rc.local file and put the command to start the script at the end, for SysV init style, it's a bit more tricky. You'll have to put a script wich starts the Tcl script in the /etc/init.d dir, and create a symlink with S<nr><scriptname> to the script in the /etc/init.d/rc<runlevel>.d/ directory to the script... the script wich starts the Tcl script must accept an option "start" to start the 'service', your Tcl script (see other scripts in the /etc/init.d/ directory for examples) and it may accept an option "stop" to stop the Tcl script (on shutdown for example). To make it stop you must make a symlink like K<nr><scriptname> in the /etc/init.d/rc<runlevel>.d/ directory. <nr> means a number from 00 to 99 wich tells the init in wich order the scripts are executed.
Greetz,
.-=~ iluvatar ~=-.