Answered my own question
Yes, it is possible to change/replace the swing keels lifting cable without removing the keel itself AND while it's on a trailer.For future reference for those that may need to perform this operation, here's how I did it.1. Keel must be in the raised position and supported from underneath.2. Completely take out the settee table and it's base that surrounds the keel trunk.3. Nudge the compression post and bulkhead forward about an inch. It's not secured to anything and will move that much. There's 2 screws that hold in the sheave that are under the bulkhead.4. Remove the six screws that hold the cables sheave and remove it. You'll now be able to look down the hole where the sheave was and see the cables connection point on the keel board.5. I drilled an 1 1/2" hole approximately 1" from the sheaves hole to work through while shining a flashlight through the sheaves hole to see.6. Using a long metal cutting blade in a sawzall to cut away the old cable and thimble.7. I made up the new cable with a new thimble and crimp using the same 1/8" stainless material as the original as this was all that the sheave would allow for.8. After the eye was on one the one end, I put on a small (no longer than 1 1/2") stainless caribiner. This was simply dropped down through the sheave hole and using long handled pliers was able to clip it onto the ring of the keel board.9. Pull the new cable through the sheave and reinstall it.10. Push the compression post and bulkhead back where it needs to be.11. Reinstall the table base.12. Reinstall the rope and pulley system and pull it into the keel raised position.13. Now take the end of the cable and pull it to see where you need to make the second eye to connect to the pulley system.14. Put the table back in and you're done.Now it looks like that when the time comes and I do absolutely have to remove the keel board, at least I won't have to take the table out to disconnect the cable I can just unclip it off from underneath.BTW, the 1 1/2" hole I just left open as I didn't see any harm from doing so. I suppose it could have been patched but didn't see the need.