I need to give my users the ability to horizontally scroll a layout (ideally, part of a layout).

I have found bits and pieces about this, but no single, coherent explanation. The help menu tells me to create a button with a script that does the following: "Scroll Window (if the layout objects are wider than one screen)". However,

1) the "scroll window" script command does not give me the option to specify that I want a horizontal scroll

2) I don't know how to create a layout object "wider than one screen".

I would greatly appreciate any help on this!

I don't think you can scroll a part of the layout horizontally (except a web viewer). Users can scroll the entire window using the window's scroll bar. Perhaps you should explain your purpose in more detail.

Essentially, I want to make a horizontal version of the vertical scroll bar that you can place in a text box.

:)

Assuming you mean a text field: if it's wider than the window, you can scroll using the window's scroll bar; if not, there's nothing to scroll, because the text wraps.

You still haven't explained the purpose of this.