Haven't been there YET, but it's on our itinerary for September, and I did a fair bit of research into how to make it happen. We will stay at Xaro lodge and they offer a package which includes a one day trip to Tsodilo. We will be self driving there, at the time of booking the only other option was to charter a plane at around $5,000US
It's a bit far to do as a self drive day trip from Maun, but there is the option to camp there (very basic facilities I understand) or to stay at Drotsky's cabins. The other accomodation possibility is a place called Swamp Stop. The road towards Shakawe is reputedly quite rough with plenty of potholes but should be achievable in a 2 wheel drive.
The third option I came up with is that Helicopter Horizons does a one day helicopter trip from Maun - pretty expensive way to do but you would also get a wonderful scenic trip along the eastern delta.
I don't think you will get there via public transport.