Highlighting regions in-game

I am trying to set up a movement system which requires you to select where you would like to move. I would like to make the regions used for the choices highlighted when the movement waiting to be selected. I would prefer this to be a square if at all possible. It only has to work on flat ground. Does anyone have any idea how to go about creating this effect? Thanks in advance.

If you are capable of creating a cube in 3DS Max, then it won't be that difficult. You need no modelling skills for this.
What you need is:
3DS Max
MDX Exporter plugin by Blizzard

Then you can use the new model in a special effect action.

If you can't accomplish this, you might want to use existing effects to mark the rect (if you use UMSWE or code Jass, you know that a region is something else). That wouln't be square, but it would highlight them in some way.

just "unhide" the circles of power at regions where u'r allowed to move...

Well I know nothing about modeling and i'm too broke for 3ds max. Guess i'll just have to stick to the ole special effects action. Of course i could just make an invisible building that had no model but left the ground model in place. I'll have to experiment with that. Thanks for the input.

Edit: Well the invisible building just looks crappy. I don't suppose anyone else out there has a bright idea?

Have you tried changing the ground texture?

I've tried the ground texture but it doesn't fill the region. It only makes a particular size. I have found no way to change the size of the ground texture.

How about using Force Walls to outline a square?

Well i must say i've never heard of force walls. What does this do and how do i implement it?

I mean the model for force wall - I think it's a destructible... it's just a glowy-looking line/crack in the ground...

that sounds pretty interesting. I'll have to give it a try also.