He has taped the backsides of the veneer pieces with really cheap masking tape and has found that the wood glue will penetrate enough to hold the pieces in place prior to sanding and glassing. The tape on the outside did in fact tear away pieces when he tried to remove them. Never the less, pieces have had to be re-made in the process either from over chiselling or breakage, but by the time he got ten in place, he found the best practice to use and is moving on quite quickly.