Attaching blades to the inside housing of the blade gauntlet can be difficult to explain. More than anything else, it's just going to require a bit of ingenuity and clever use of materials on your part. There's all sorts of different ways a person can mount the blades inside the blade housing area. Since you didn't mention anything about using any kind of blade extension system so I'll just assume you're going to install them in a permanent stationary position.
To do it this way, I think the best method would be to attach the rear ends of both blades to a single mounting block and then secure the mounting block to the upper area inside the blade housing. To make a mounting block, you can use something as simple as a small block of wood, cut to a length that's equal to or slightly larger (1/8" to 1/4") than the space in between the housings two front blade openings/slits. Use two screws to secure each blade to opposite sides of the mounting piece. Then, you'll just need to attach the mounting piece to the inside of the blade housing. You could simply use some type of adhesive such as hot glue, epoxy resin, etc. or you could also use some screws or bolts to attach the mounting block to the inside area of the blade housing.
Remember, there's no "one" way to do this so you may have to try a few different ideas out before you find one that works best for you. You may also just find it easiest to take the blades & blade housing piece w/ you to your local hardware store and ask the staff to help you come up w/ a few more possible ideas for how to do this. Most people who work in Hardware stores are usually very crafty when it comes to problem solving solutions and fixing all sorts of misc odd applications.