There is an even better solution to this problem. First you need a TIN... which you already have or you wouldn't be here. Next you need to convert that TIN to a multipatch by using the Interpolate Polygon to Multipatch Tool. This tool takes any 2D polygon and 'drapes' it over a TIN surface to make a 3D multipatch of the polygon. If you want to convert the entire TIN, you'll need a polygon that covers the entire TIN. Once you have your multipatch, all you need to do is convert it to a Collada file, using the Multipatch to Collada tool. Once that is done, simply import your Collada file into sketchup and bingo... you're off to the races.
Thanks Chris! I am in a totally different career now, 8 years later, but
hopefully others will find this workflow useful.
Patrick