Well I got this contour site drawing from someone else and had a reference image which had the elevations written, but no tags were present in the drawing.
I am done with it now though, I raised the contour lines manually in AutoCAD and then imported the 3D into SketchUP.
Though I would still like to know the lisp for doing it via text tags in AutoCAD.
Here the contours were brought in from rhino. I otherwise usually use global mapper to get conotur maps.