First of all, you need to know which coordinate system your data is in; the CAD guys should be able to tell you this. In the UK, for instance a common coordinate system is OSGB36. See the FAQ for information on projections and datums.
Next, you need to know the coordinates of a point (normally the origin) in the CAD file. Technical artists often don't care where the drawing is in relation to the rest of the world, so you may have to ask about. Once you know where the drawing's origin is in the real world (or at least your projection of it), it should be a simple task to ask the CAD guys to offset the origin to the coordinates you have. You may also need to get them to rotate the drawing so north is up, and to scale it so that 1 unit in the drawing is 1 unit in your projection. this is usually in metres, but can be in feet if you're dealing with US data.
For instance, say your CAD drawing is of Buckingham Palace, and the origin is the statue of Queen Victoria in front of it. Let's assume the data is in OSGB36. You would need to add the coordinates of the statue (529155 179739) to the origin of the drawing to place it in the right location.