This post is very useful to understand the whole process. Thank you all of you for sharing your experiences. I am planning to go next week to San Ysidro Transit Center. If anybody is planning to go, please let me know.
In addition, I wanted to confirm if following documents would suffice:
1. old and new passport
2. last 3 pay stubs
3. offer letter
4. original i797
Do I need to get separate letter from employer stating that I would be travelling to mexico for i94 renewal purpose and that i am still working at xyz company?