Either you or your wife can apply for it but your passport etc will be needed.
You should include all the documents you can to show that your wife's son qualify for an EEA family permit.
As a guide they should include:Â
a copy of your EEA national passport (endorsed by your embassy in the country of application); andÂ
proof of their relationship to you (for example, their birth certificates or marriage certificate); and
a letter from you declaring that you are travelling with them or that they are joining you in the UK.
If they are not your spouse, civil partner, child or grandchild under 21, they must provide proof that they are dependent on you or have lived as part of your household.
Check this website for further details;
http://www.ukvisas.gov.uk/en/howtoapply ... ionals#Top