The shell can be started by double clicking on the program name (M2TSHELL.PRG). A screen-wide form appears. This form contains edit fields for the different options. To edit a box first click on it with the mouse. The cursor appears in the box and you can use the keyboard to edit the string. You should not include the option identifier in the string. Only the parameters should be entered. For instance, if you want to skip tracks 2 and 3 just put 2,3 in the box and not -s2,3.
One exception is the 'other box'. Here you can enter other valid MIDI2TEX options. As this box is not tied to a specific option the option identifiers must be included if this box is used. Currently there are no boxes to allow selection of the alto clefs. The only way to select them using the shell is by inserting proper option strings in the 'other box'.
A file can either be selected by editing the file selection box or by using the file selector by clicking on the button above the file selection box.