Sass,
Time and motion study require learning and practice. Here are some references that will help you aquire the learning part: http://www.iienet.org/public/articles/index.cfm?Cat=452
The book, http://www.wiley.com/WileyCDA/WileyT...471059056.html
seems to be a more popular one.
It would be a good idea to get practice under an experienced Industrial Engineer before you start one. There are many techniques and allowances that are involved in this study.
Regards,
Govind.