Thanks for the question. This can be done by nesting generators and using the Segment Y Role macro.
In the graph above the L1S generator (1) create the column. It's created using two objects: a base and a repeating wire section. I've exported the XSize so you can easily adjust it from the Modify panel.
This is wired to the X Evenly, Start and End inputs of an A2S array (2).
To get it to appear only where the X evenly columns and Y Evenly rows intersect, you can use the Segment Y Role Macro. This macro adds several additional inputs to the A2S generator when wired to a columnar input. By wiring the L1S generator to the Evenly, Top, and Bottom inputs you can create a grid that's adjustable using the X and Y Evenly Distance settings. To "trick" RailClone into thinking that the Y Evenly and Top inputs are being used, wire an empty segment to their inputs.
The file is attached for reference.
I hope that helps, please let me know if you have any questions.