The ML-L3 is for Nikon consumer cameras where the 10 pin socket is replaced by an IR release.
The D700 is a pro camera and has the 10 pin socket - hence no IR release built in.
HOWEVER - as I understand it the ML-3 doesn't use the flash connections as the release mechanisms are all routed to the 10 pin socket not the flash shoe. The ML-3 is fitted to the flash shoe only becuase that's the most convenient place to locate it and hold it steady. There is no reason why the ML-3 can't be fitted to some other location with tape. The governing factor is the length of the connecting wire and even that can be lengthened using an MC-21 extention cord.