How do you create a custom helper?

I want to create a custom helper object which is a point with a direction.  Can anyone help guide me along the proper path?

What I have right now is a helper tool which creates a cone on mouse click but as soon as you move the mouse, it dissapears.  If you don't move the mouse it creates a cone in the scene, but also a dummy object. As far as I can tell it won't let me create just a cone because I have to extend something.  There doesn't seem to be any type of helper object which has a direction of some sort which I could extend.  Most of this code is cobbled together from whats in the help file:

plugin helper myConstraint
name:"myConstraint"
classID:#(0x6b4889fb, 0x5da01536)
category:"Standard"
extends:dummy
version:1
(

    rollout params "Parameters" width:160 height:248
    (
    )

     tool create
     (
        local p, createpoint

        -- define a function to perform actual node creation. Setting coordsys to
        -- ‘grid’ in order for the alignment of the node’s local Z axis to be
        -- perpendicular to the construction grid
        -- fn createpoint = in coordsys grid p=point pos:gridPoint
        --
        -- set up so that a node is created on a mouse button down, move node
        -- drag, release node at mouse button up.
        --
        -- if clickno == 1, then we are at first mouse click, which is a mouse
        -- button down. If clickno != 1, at following mouse button up.
        on mousePoint clickno do (
            if clickno == 1 then (
                -- createPoint()
                --in coordsys grid p=point pos:gridPoint
                print "Click == 1"
                in coordsys grid p=Cone pos:gridPoint smooth:on heightsegs:1 capsegs:1 sides:5 height:39.3701 radius1:3.93701 radius2:-50.3244 mapcoords:on transform:(matrix3 [1,0,0] [0,0,1] [0,-1,0] [-5.98291,-4.23415e-007,9.68661]) isSelected:on

                -- if p == undefined, then clicked twice without mouse movement
                -- (double clicked). No point object present, so just ignore this click.
                ) else if p != undefined do (
                    print "Setting p to undefined"
                    p.pos = worldPoint
                    p = undefined
                    #stop
                )
            )

        -- if p != undefined, we are moving a previously created node
        -- if p == undefined, and left mouse button is down, create a node

        on mouseMove clickno do (
            if p != undefined then (
                print "MouseMove p != undefined"
                p.pos=worldPoint
            ) -- else if lbutton then (
--            print "MouseMove p == undefined"
--                -- createPoint()
--                in coordsys grid p=Cone pos:gridPoint smooth:on heightsegs:1 capsegs:1 sides:5 height:39.3701 radius1:3.93701 radius2:-50.3244 mapcoords:on transform:(matrix3 [1,0,0] [0,0,1] [0,-1,0] [-5.98291,-4.23415e-007,9.68661]) isSelected:on
--            )

        )

    )    

)