You mean the toolbox written by Dr. Richard Schreier? I'm sorry, I can find any information about clock jitter from this toolbox. Can you give me any detailed information?
Check Dr. Piero Malcovati's and Dr. Simona Brigatti's toolboxes at Matlab file exchange central. If you can't find the jitter model you're looking let me know i have some simulink noise models for sigma delta modulators.