Yes, it can, and should be done. I did the same for the same reasons, the lap belts are worhtless.
Just read an article on child injuries and they concluded that many times injuries are fatal because they tend to be internal, lower abdoemn type, which dont immediately present, and thus are not treated until late in the event. These injuries are the result of lap belts that are too high on the child.
There are some booster seats that have thier own, 5 point, belt system rather than using the vecile belts. I dont like the seats that simply realign the belts because it is a kluge. It is not the best possible solution and error prone. Nothing will perform like a good 5 or 6 point harness. I am in the market for one of these boosters now.
The lower mounting tabs are in your vehicle, a simple bolt-in. Go to a junk yard and buy some good looking belts, check for cuts, scratches, stretching, mold/mildew. The upper mounts are tack welded in, and could be drilled at the welds to remove. The alternative to removing the ones in the junker, is to make your own. You can measure whats needed because your vehicle has the holes already there. The belt mounting hole with threads, and two bolts holes forward and aft. Note that there is no mount in the C pillar in the 4 door, as someone said. It is in the sheet metal along the upper horizontal piece along top of the window. Then all thats needed is some cutting along the bottom of the rear window to feed the belt through, and some cutting in the plastic trim. You might want to get the two plastic trim pieces that feed the belt up to look nice.
Easy job, maybe a couple hours with the tools. Hardest part is the upper mounting plate, either fabricating one or removing the donor part.