For those, who have not see this yet: @victorshoup and @JensGroth of the DFINITY Foundation have published their threshold ECDSA work which is the foundation for our threshold ECDSA implementation. You can have a look at the paper uploaded to eprint at the below URL.
Design and analysis of a distributed ECDSA signing service
Jens Groth and Victor Shoup
DFINITY
Have fun! 