A medallion stamp is simply a notion put on certificates, and/or letter that represents that a bank and/or a broker/dealer attest that your signature is in fact your signature and your instructions are yours. It s basically a "signature" guarantee.
If the shares are currently being held by a bank and/or brokerage firm, talk to the holder and they can direct you and provide you with what is needed. They can also affix a medallion stamp you their forms.
If you are holding the certificates, take them to a major international brokerage firm (Merrill Lynch, Morgan Stanley) and/or bank (CITII). They will be able to provide you with what you need.
Also, if you re holding the certificates you could contact the transfer agent (their name is on the face of the certificate), they will be able to walk you through the paper work you will need.
The Last thing you need is a lawyer, why incur expenses when banks, broker dealers and/or transfer agent can and will do it for free.
Good luck, been there, done that
from THE STREET