Most children are put in preschool more for the social impact than for the educational one. You really don't need any special "tools", you proably already have everything in your home. You can use any type of plastic containers to teach concepts like in and out, or small and big.
I'm sure you have books that you can use for story time, or better yet make weekly trips to the library. The library should also have programs that will help him to interact with other children.
One of the things my kids get in preshcool was to cover the tables with a table cloth and dot with shaving cream. Draw letters, numbers and shapes in the shaving cream.
Create a small corner in your home for "educational" time. Write his name in big letters. One concept he should learn is how to recognize his name, and possibly write it.
There are tons of software available. I always liked the "Jump Start" series. Not that he should be spending lots of time on the computer, but 15 minutes a day, or 30 minutes every other day.
And don't forget about recess. Take him to the playground. This too can be a fun way to teach. Climb UP the lader, go DOWN the slide, crawl THROUGH the tunnel. He'll also have the opportunity to play with other children.
Join a playgoup.