ZBrushR7 - ZModeler tip
I decided to buy Zbrush 4R7 because with the ZModeler tool, I don't need to model in another software now.
ZBrush doesn't allow Ngons while modeling, so insert an edge between two triangles can be a bit tricky.
Here's how:
Delete the triangles you want the inserted edge to go between (otherwise the insert edge will proceed further than required).
Insert the edge loop.
Use the Close edges tool to fill the holes you deleted
Delete the added edges, leaving a nice quad you can nudge into place.
A special case would be where the triangles you want to insert an edgeloop between are on a border, because in this case the Close tool will fill the open edge too.
In this case, just do as shown below:
Steps when inserting an edge loop between two triangles on a border.
Delete the quads below the triangle
Insert the edge loop
Close the holes
Delete what edges you can (ZBrush won't let you delete them all as it would produce Ngons)
Stitch away the vertices (like target weld) and delete the unecessary edges.
Nudge result to suit
Sorry for the poor compression of the GIFs.