As VK himself indicates in the original MDK, always use custom actions with custom superweapon types. Also note that like the original Action types, custom ones may only be used once in superweapons. The attack cursors, however, may be used multiple times.
First, create a [MouseCursors] section.

As such,
[MouseCursors]
NewPara=259,10,4,516,-1,12345,12345

The line works like this;
NewAction=[StartFrame],[NumberOfFrames],[AnimationInterval], [MinimapFrame],[MinimapNumberOfFrames],[HotSpotX],[HotSpotY]

Basically, it starts with the frame at which the animation will start from, then the number of frames to play, the next value is always 4 so use that for the interval, then you have the minimap frames and then the hot spots (IE; where the cursor will display). However, keep in mind that the maximum length of your action name is only 32 characters.

HotSpotX and HotSpotY can be set as "0", "12345" or "54321", which correspond to left, center and right for X and top, center and bottom for Y.

So, for example, if you set 12345, 12345, the cursor will be dead center, which is the recommended setting for cursors drawn on the battlefield.

The MinimapFrame can be set to -1 to simply disable its use.

The frames are, of course, related to mouse.sha; also bear in mind that frame numbers are zero-based. The provided example would create a new para cursor, which can be used once on any custom superweapon of your choice.
Action=NewPara ; This is simply the name of your new mouse cursor entry.