Copy the shortcut to WET and copy and paste this line into the target, remember to put a space after the " before pasting this.

+set fs_game tcetest +set seta com_zoneMegs "128" +set com_soundMegs "64" +set com_hunkMegs "256"

Using WET/Mods menu may or may not work. Editing the cgf files may work for some users but not all. For thos enot familiar with cfg editing, I suggest not to tamper with them, just use this shortcut method.