Did you even look at the dd-wrt web site?
As to tomato, use google. I did.
I have a Asus RT-AC68U router and currently I can't seem to find a guide on how to actually install DD-WRT / Tomato on it does anyone have a link to a guide or the knowledge on how to do this I look at this and feel oh god what if I brick my router.
Welcome To SNBForums
SNBForums is a community for anyone who wants to learn about or discuss the latest in wireless routers, network storage and the ins and outs of building and maintaining a small network.
If you'd like to post a question, simply register and have at it!
While you're at it, please check out SmallNetBuilder for product reviews and our famous Router Charts, Ranker and plenty more!