Dennis is only using the tape over wadded up newspaper to fill in small spaces between the real rocks along the edge of his layout. He is not recommending it to cover large areas, although similar methods are possible after you've gained some experience with more traditional methods.
Check out my response on your other thread, and consider the other book I mentioned there. Between that book and the one by Dennis Brennan, you should be all set to start scenicking. 
Jim
