There are many ways you can do it in the older software:
1 - Go to Aux activate the Tool and jog to cut then deactivate the tool
2 - Aux to activate the tool, click on Point where you have entered a distance for either x or y and a feedrate and press Move then deactivate the tool
3 - Or my preferred way. Jog to edge of material and Set Program Zero, click on Midi enter the gcode such as G01 X48 F70, Press Start and it will activate the torch cut in the X axis 48" at 70 IPM and then turn off the tool automatically.
In TM4 to see the Midi button you may have to go to Configuration > Preferences > Main Screen and place a check next to Midi, also you can go to I/O > Output Lines and change the field to Yes in Display in Output Box to place the Plasma button on the Main Screen.