The answer is each of the carrier "conditions" has a different TACAN value (X42, X43, Y43 etc). I am assuming you have all of these carrier configurations in you SimObjects/Boats folder.
If you look in the unzipped RFN folder you will see a folder "For AI Carriers". This contains all of the carrier TACAN frequencies used in the RFN gauge. Copy the section you require, beginning with [Formation.xxx] and paste it into the cvn_68_69 folder in AI Carriers. But remember to adjust the Formation no to the next one in the sequence. (Cvn.. can be opened in Notepad.)
Close and re-start FSX, then press Shift + J and set up your carrier so RFN can "see" it. It will show in the AIC carrier menu as USS Nimitz TAC 37X or whatever. If you read the manual you will see all of the carriers and their TACAN values listed, (carriers of all nations are shown) there are 78 carrier choices and many airbases listed (including El Centro RWY 26 TACAN 104Y) . Then tune the RFN to the allotted frequency and the ADF needle will point at the carrier's location and distance. On approach click on TACAN and the gauge becomes an ILS.
Further, if you are on an airbase near the sea, you can teleport yourself onto your chosen carrier's deck. Set up AIC as before and ensure the carrier is moving forward. Then
1. Start RFN,
2. Dial in the TACAN frequency If the carrier is within 100 miles the gauge will be active. I use a waypoint about 50 miles off the coast to locate my carrier.
3. Press keyboard Y (slew command)
4. Press Go To A menu of possible positions available will appear
5. Select one of them
The plane will be "teleported" to your required location.
When I do this the plane moves to the required location, BUT, in my case, it is at sea level inside the carrier. To overcome this I press Go To again, select the required position (again) and this time I am stationary on the deck.
6. Press Y to stop the slew action.
This program works "within" AIC so all the carrier "Turn left, right" commands etc are still active.
Also, once you are on the catapult, as usual Press Sh+U, Sh+I (user lower case letters, not capitals), then use your joystick trigger button (Button 1). This will launch you off the deck.
Interestingly, the RFN TACAN's are independent of the FSX radio frequencies. Thus I have Dino's T-45 IFLOLS in my Texan tuned to the RWY 26 ILS (108.70) using the FSX NAV1 and the RFN tuned to 104Y and both work.
It is a truly wonderful program and can be highly recommended.
I hope this helps
Good luck,
Tregath