Ah, you’re wanting to export a texture template. The closest you can come to doing that in ZBrush is by using Tool
Texture
Uv>Txr. But this won’t give you the polylines.
I’d just use the free version of UVMapper to generate the kind of template you’re looking for.
But why are you wanting to bother with that? It’s the old way to work, back when it wasn’t possible to paint directly on the 3D model. When you paint on a 2D map you must manually compensate for UV seams and texture stretching. When you paint directly on the model you let the computer handle that compensating and can paint what you want to see. Additionally, thanks to ZAppLink you can send your model to Photoshop when you need to, then bring it back to ZBrush and have what you did in PS applied to the model.