You will definitely have to unbolt one side of the front beam in order to gain access to the trampoline groove in the beam. You will probably also have to loosen the opposite side of the front beam so you can lift it enough to slide in the bolt rope.
I never removed the center bar - but I think it just slides into the aluminum fittings that are riveted to the beams. If this is true, then you should just remove the entire front beam, slide it forward to clear the bar, install the trampoline, and reinstall the front beam. The installation can be a bit tricky because the trampoline wants to pull the hulls together without the beams installed - then it's difficult to reinstall the beams. Try to do the installation in bright sunlight so the sun will warm the trampoline. It will be easier to stretch things into place this way.