I have a CIX 100 I'm trying to program so that CO line five can only be accessed by one extension, and that line only rings at that same extension. Right now if an incoming call on that line is not answered it starts ringing another extension, even tho it doesn't have that line assigned to a button. The intercom button starts to flash and the phone rings. On the old Toshiba systems you could assign which extensions had access to individual lines in program 40 but I can't find that option in the program cross reference materials between the new and old systems. Any help would be greatly appreciated

Well, there isn't a program 40 in the CIX. For outgoing access you could typically not include the CO lines on the keys, and the users could only dial 9 or use the #7 line access codes, which you could restrict in COS.
It seems like you have an incoming ringing issue. Many times you would see the COs set to ring based on the key assignments. If the keys were on the phone and set to ring, they would ring.

This changes when the ringing destination is a Multiple Call Group. With a MCG the key assignments are ignored and only the extensions in the table will ring. Also, the extensions ring on their Intercom key, which will flash green while the CO line will flash red, and the extension will ring even if the CO is not programmed on the keys.

The closest thing to program 40 of the DK is the FRL level on the CIX. I don't think you need to mess with FRL. Instead, check the DIT of CO line 5 in Trunk Assignments and make the destination the target phone. If you want to keep line 5 from the dial 9 pool, you will want to create a new OLG (just copy the settings from OLG 1) and assign that OLG to line 5 in Trunk Assignments.

We are assuming here that the phone that you want to have line 5 doesn't have a call forward no answer set.

Good point Skunky. If you DIT to the DN, it will follow the call forward of the DN.

you could double click on co line on phone and you can disable outgoing permission for that particular co line on that phone. inbound stuff will still work for that co line similar to dk pgm 40