Needing a programmatic insertion of DD

Hello.
I need an API or something-like in order to programmatically add DD attributes to a "main" record.
For example, 2 DD attributes are assigned to "roles":
- TVAcode
- firm
What I need is a mechanism in order to add values contextually to a "role" creation, for example passing an array
array('TVAcode'=>'07987879987','firm'=>'My Firm')
to an API, WITHOUT use of forms, templates etc: only APIs, and perhaps some direct querying to the DB.

Someone knows if it's possible ? Any idea?

Thanks in advance
Federico