There are multiple equipment setup options to choose from within MAGNET Construct. Check out this video for an overview of the tradition method commonly referred to as "occupy / backsight".
In this method, the Topcon LN-100 has physically been set over an existing control point on your project site and is then expected to be oriented towards a second existing control point.
The MAGNET Construct app will then drive your Topcon LN-100 and solve for it's orientation. Could not be easier.