Knowing it can be done is 95% of the battle. Plus if the local expatriate British retired engineer tea shoppe owner can do it so I'll give it a go. Essentially you take the French Press and remove enough of the shank so the strainer is fixed near the top of the pot. Move the plunger to the top of the pot leaving enough room to filter tea at the spout. You think the spout is covered but look into the pot and make sure there is no gap between filter and contour of glass creating the pour lip. Mark the shank where it protudes from shank spacer about 1/8 in. A fat marking pin is perfect. My biggest surprise the shank is solid metal. You'll need a hack saw to cut it above scribe mark. I was expecting to crimp the shank so the filter wouldn't fall back in pot. You can't since it solid. My solution press a plastic wall ancher over the shank making a snug fit so the anchor base rim is just just below scribe mark. Cut top of plastic anchor flush with cut shank. This will exactly line up the depth of the filter you measured first. In my case the handle for moving the plunger is a lid. It is hardened plastic and the shank scored so it is can be pressed into the plastic lid while hot. You'll wrestle working this loose. Since it is hardened plastic the opening can be widened with graduated drill bits till the lid fits snugly over the plastic anchor. In this case it didn't take much since the cut wall anchor wasn't that much bigger than the shaft. The lid for the shank handle becomes cosmetic and loses it functional of moving the plunger. The engineer used hot glue to secure cut shaft end of plunger to lid. I used a wall anchor and enlarged lid opening because eventually glue and hot steam don't mix. You end up with a damn nice teapot with glass for body and plastic for handle and body cradle with loose tea filtered by strainer at top of pot with no plunger which visually doesn't get in way of watching the infusion. I always invoke the 50% rule when making tea in a glass pot. When half of the leaves start to settle in the pot it is time to drink the brew.
Jim