Start by fastening temporary wood blocks to the rafter tails (Image 1). This will protect the original porch wood and support the temporary beam. Join two sections of 2x6 for the temporary beam. With the sections joined, sister the two to create a 20 foot length (Image 2) which will span the porch. To get to the existing header, cut away the nails that attach the box beam (Image 3) and mark and remove some of the facing boards (Image 4).
With the old beam uncovered, the temporary beam can be placed on the braces you've made (Images 1 and 2). This will hold the weight of the porch roof while replacing the beam. Move the braces into place on top of the bottle jacks (Image 3), then raise them till they support the roof. A bottle jack is a small hydraulic that uses a long handle to raise and lower support braces.
The next step is to remove the "L" brackets that hold the existing beam on to the posts (Image 1). Then the old beam is free and ready to be removed. This may take several people to accomplish (Image 2).
Before putting the stronger beam in place, jack up the porch roof 7-3/4 inches to make room for the new taller beam (Images 1 and 2). Now carefully remove the bracing and lower the porch roof on to the new beam (Images 3 and 4).
Cut the wood you'll use to wrap the new beam. Cut a 45 degree angle so the edges will be properly mitered for a clean look. (Image 1) . Nail a fill strip at the top and bottom of the beam, which will bring the trim board to the desired width (Image 2). Attach the trim piece to wrap the beam (Image 3).
Begin by creating a temporary beam out of 2x6s, screwed together. Create temporary "hogbacked" supports by nailing 2x4s together. Cut to the required height to allow for the bottle jack and the height of the column to fit under existing porch ceiling.
Temporarily secure the temporary beam to the porch ceiling and place both the bottle jack and the hogbacked column under the beam. Begin to elevate the beam enough to allow removal of the existing porch header.
Cut and place new 6x6 treated columns on post anchor bases and temporarily support with cross braces. Prepare the new LVL for installation by cutting to length. Raise into position and secure the 6x6 columns below using the required seismic anchor. Carefully lower the existing porch ceiling onto the new beam and remove all temporary walls and bracing. Secure all the rafters to the new LVL using the required seismic anchor.