It should work with a red laser pointer (if it's bright enough). For the slit, I suggest taking razorblades - I've seen one made that way before. Alternatively, we could ask John if he can cut us a little double slit from sheet metal with the NIR laser. That one should have a small enough beam and it should come out nicely.
I also have a bright 405 nm laser diode in case a standard red laser pointer (I use the cheap ones from Walmart - usually close to the counter) are not bright enough. Let me know when you want to start this and I'll be happy to help.