<p>Is there a mechanism to inject dependencies into Linq to Sql or entity framework entities? If so would it be a sensible approach?</p>

What exactly are you after? Note that you can use LINQ-to-SQL without the attributes, if you want to use existing classes... you need to use an
external xml file
to hold the mappings, and an
```
XmlMappingSource
```
.
Note that this won't work with Entity Framework; only LINQ-to-SQL.