First of all, let me start by saying that I haven't repaired or replaced a Hi-Lo bulb seal, so I am not sure if this will apply.
I have successfully repaired bulb seals by cutting away the damaged portion and splicing in a new section. I've done this with hollow cross section bulb seals and I don't know if the Hi-Lo seal is hollow or solid:
1- Cut away the damaged portion using a sharp razor blade knife. Ensure that you have a clean, straight cut.
2- Cut a length of new seal to fit the area you are repairing.
3- Make a filler to fit inside the bulb. The filler should be 3-4 inches long. You can use a very soft rubber hose that fits inside the hollow bulb section. You can also cut a small length of bulb from a smaller seal, or make a filler from strips of the damaged seal section. The idea is to have something of similar give as the bulb seal inside the bulb section of the repaired area.
4- Get some automotive contact cement, the type used to glue sunroof seals. An auto body and paint supply place should have this.
5- Spread some glue inside the hollow bulb of the old seal and the repair piece, as well as the faces where these two pieces will mate. Spread some glue on the filler piece.
6- Insert the filler into the old seal leaving a few inches sticking out.
7- Glue the repair piece to the old seal by inserting the few inches of filler that are sticking out into the repair piece and pressing everything together. Secure/press together for a while. Let dry overnight.
By doing the above I've avoided removing and replacing long bulb seals completely. The repairs have been permanent. The only downside has been that the bulb seal ends up being a bit stiffer in the repaired area.
Raul