Is this what you're looking for? I'm assuming that by "Xcoord" you're referring to the current X-position of the mouse, you want to maintain the existing Y-position of the mouse, and you're going to use some arbitrary integer X.
Set integer [X] value to 2
Write '[Blue] Starting Mouse Position: Xcoord = {MOUSESCREENX} ; Ycoord = {MOUSESCREENY}' to log
Set integer [Xcoord] value to the converted value of {EXP:{MOUSESCREENX}+({INT:X}*90)}
Move mouse cursor to screen coordinates by text/token X:{INT:Xcoord}, Y:{MOUSESCREENY}
Write '[Blue] Ending Mouse Position: Xcoord = {INT:Xcoord} ; Ycoord = {MOUSESCREENY}' to log