I believe others have talked about this on this forum - I think I even went into some detail regarding this, if you'd like to search for it. But generally speaking, you can use a combination of jacking and raising/lowering the tongue jack to end up supporting the keel on blocks/wood. To some degree, the actual way you will do this could depend on your trailer/frame setup and bunk(s) placement. You can get the entire boat raised off the trailer, but it's not really necessary for this task. Raise the bow keel enough to get it off the bunks and place cribbing underneath. Jack the stern keel the same way and list the boat onto the good bunk. Place cribbing under the stern keel and secure the boat so it stays listed. Good to go from there.
My #1 rule: The only things that go between the hull and the bad bunk are things that you don't mind possibly crushing.
