Asking for a letter of reference

Why do I feel guilty or like I am some how cheating the system?

Short story: I have been trying to attain a competitive position within my company for the past 3 or so years. I have unsucessfully interviewed more than a few times for the opening/similar openings only to watch applicants that I trained or who had far less education, experience, and training advance.

It's been frustrating, but I work in the public sector. Nepotism, popularity, minorities, and being a "yes" man are highly desirable qualitites.

I was approached by someone from a different public sector who is influential in my field and ultimately over sees all of the work/product that my company is responsible for monitoring and told that when I applied again to give him a call.

My question is, how should I phrase my request? I respect the person a lot and don't want to come off as entitled or demanding of any influence he may be able to impose.

I drafted an email to send and attached a copy of my CV/resume. Should I come out and ask him for a letter or should I just let him know that I will be applying again and would like to get advice/guidance from him in the hope that he makes a few phone calls on my behalf?