Hi, Sam, If youre going to cover the treads and risers with an oak plywood, try to match the colour ( important) because there are so many types of oak,(American/English/Japanees) and use a good wood glue, and thin lost head nails. you will have to put an oak nose ( front of the tread) so it will match the rest of the tread, ( I my self would try and use an "L" shaped piece of solid oak, with the front rounded off. fit the tread first, then the nose, then the riser, ( the riser panel is laying on top of the tread panel, ( and easy to fit) you can fit a molding bead between the riser and the hardwood nose glue and pin ( nail). you are thinging of useing 1/4" ply then remember to let the nose come up also 1/4" higher than the tread that is there now,. Try and start at the top and work your way down, remember that the new "tread" is 1/4" higher than before, so you may have to rase the carpet up to the new tread. Fitting the plywood will be hard, it will have to spot on, so take your time in fitting it,and remember " If it's worth doing then do it well" But there will be others on the board that will give some other ideas, so compair and see which you think is better/easyer.