Marlon,
My attorny provided a template, and I had to work with my HR dept, to get the customized version. HR did add a few things in letter like "company is employment-at-will" cause, that attorney did not like so much.
In the top, it says "TO WHOSOEVER IT MAY CONCERN". Then it is pretty generic, mentioning job title, salary, full time time employee etc.
However at the last paragragh, it does mention "Accordingly, we respectfully request that you grant him approval of the I-485 Application in order for him and his family to obtain their permanent residency status soon.
The attorney did provide whole bunch documentation about AC21 provisions, USCIS memos about AC21 etc. and did a very proffesional job.
I had mentioned to HR, that I will need one EVL letter immediately after I join and they happily provided it to me. The funny thing was I had to get the same letter not once but 3 times, once for invoking AC21, second time for RFE response and third time just before the local office interview.
The EVL is the only thing that the interviewer looked at for my part of the interview, made me wonder why they didnt approve after RFE reponse.
Best of luck to you..