This page used to contain instructions for installing the Enblend and Smartblend plugins in PTGui. PTGui 12 and later no longer supports these plugins.
The blender in PTGui Pro 12 supports optimum seam placement and zero overlap blending, which should give much better results than Enblend and Smartblend. Moreover it is faster and it can handle arbitrarily large panoramas.
If you need to use Enblend and Smartblend though, PTGui 11 can be downloaded from your account