Same alarm will work. Mount one side on your sliding door frame, and the other will have to mount on a block on your sliding door. As long as you line them up when the door is shut, the alarm will go off when the sliding door is open. Check the code, to see if particular type of alarm is specified. Electronic, etc. etc. If not, then a string of jingle bells hanging off the door will work fine. I can understand the alarm in the pool, but requiring that you alarm the doors from your house,,,, too much intrusion on this little bit of code. I guess they never heard of locking the door and watching your kid.
You have a mainframe in your home? Wow, you live in a big house Or try clicking 'Start' then 'run' or for XP, dos is accessible in the accessories list under 'command prompt'. Hope this helps and you find the mainframe..