text cursor's location and look

[kweto]

Is there a built-in MC command, function, message, or etc. which I can use
within a script to:

1. know or control the text cursor's location within a text field, e.g.,
"put the textCursorLoc (?) between the 18th and 19th characters of line 3 of
field "fText";

2. change the shape of the text-cursor, for example, from a flashing I-beam
to an underscore.

I'm creating a text-input interface which relies solely on mouse-clicks and
button objects. No computer keyboard or mouse cursor can be used, since I'm
trying to recreate how a (Japanese) cell-phone relies on only its
alphanumeric number-pad to enter text.

Thank you.

--
Nicolas Cueto