This could be a great opportunity for you.
If your friend hasn't done so, ask him to write a formal introduction via mail (with you cc). You can then reply with a short and polite email. I would mention the following points:
- brief summary of your background
- why you want to work for firm XYZ
- what you would discuss with the person
If possible, try to meet in person. Otherwise arrange a phone call. Once the meeting/call is over, send a follow-up message. After about a month, send another follow-up message describing how you were able to implement the advice. When you apply, write another message with your CV so that the person could potentially forward your mail to HR.
All the best,