Select a section of your porch where the lift will be installed. An ideal location is right next to the stairs, but regardless of where you decide to put your lift, it is important to make sure that there is a rain gutter overhead to prevent water from falling onto the lift and an electrical outlet to power the lift. Remove any overhanging branches from that area.
Remove the section of handrail where the lift will deposit its rider. A portable reciprocating saw has enough power to cut through a wood or metal handrail. The opening doesn't have to be as wide as the lift but should be wide enough to accommodate a wheelchair and its rider. Measure beforehand to ensure that you remove enough of the handrail.
Replace the handrail with a lockable gate. Some lift kits come with a gate that should be installed according to the manufacturer's instructions. If the kit doesn't have its own gate, one can easily be made using fencing lattice and 2-by-4 lumber. Cut and nail together a frame using the 2-by-4s, then screen in the open area with the lattice. Attach two hinges to one side and a gate lock to the other. Hang it in place.
Build a sturdy base for the wheelchair lift. Make a frame slightly larger than the base of the lift using 2-by-4s. Place the frame where the lift will be based, and cover it with a sheet of plastic. The plastic will form a vapor barrier between the ground and the concrete base. Mix the concrete, according to the product instructions, in a wheelbarrow. Fill the frame with concrete. Remove the frame when the concrete has set. Cut away the excess plastic.
Assemble the wheelchair lift according to the manufacturer's instructions. Place the lift on the base, and secure it to the concrete with anchor bolts. To cut the holes for the bolts, use a drill with a concrete-cutting bit the same size as the anchor bolts. With the anchors in place, secure the lift with nuts and washers. Plug the lift in to give it power.