overland, you can cross from Turkey to Georgia at the Sarp border crossing. From Georgia you can cross to Russia at the Kazbegi - Verkhni Lars border crossing.
I did both border crossing last year, no problems if you have the necessary visas.
Sarp border crossing is very modern, quick and easy. in about 20 minutes you're on the other side.
Regarding Kazbegi-Verkhni Lars: AFAIK, no visas are being issued at the border. If you get there, you need to have all the relevant visas in your passport beforehand. If you don't need a visa either to Russia or Georgia - you need nothing, just get there and easily cross to the other side (from both sides).
As to October 2012, the border was not open all day. As far as I remember it was open at 8:00-21:00 (maybe 7:00-22:00).
Moreover, the crossing was slow, as there was a big line, and each car was being checked (roentgen check). It took me about 2 hours to cross each time. If you arrive earlier, it is better.