There's no way without coding it right now, but it'll be built in in the future.
If you want to try working it out for yourself in the meantime, the input checks are in engine-extensions/dialog/src-ext in the following three files: DialogOptions.hx, FlowScripts.hx, and SkipScrips.hx. If you search for "Input" in those three files you can see all the checks for key presses. You would want to replace them with Input.mouseDown, Input.mouseUp, Input.mousePressed, Input.mouseReleased, Input.mouseX, and Input.mouseY as desired.