Note: This is tough sometimes for camera paths. It often seems better to do them manually.
- Go to Edit Mode, select an edge loop, type Shift-D to duplicate it, then P to seperate it from the mesh. Now the edge loop is it’s own mesh
- Select the newly created edge loop mesh and go into Edit Mode. Now go to the Mesh menu and select the Edges to Curve script. This will turn the edge loop into a path, which you can then turn into an IPO curve.