setTextSelection

Help Contents Communication Terminal Access setTextSelection
overwriteMode enableTextMouseEvents

setTextSelection startposlist endposlist

command. Sets the current selection in the text console to the range from startposlist to endposlist. The poslists should be valid cursor locations.

Example: 

setTextSelection [1 1][10 1]
setTextSelection [0 0][0 0]

Reference:

overwriteMode enableTextMouseEvents