How Do You Pass A key?

Hi Everyone,
I'm new to SL and am having trouble finding some answers. I've looked through the LSL Wiki and am just not finding what I need.

I want to create a door mat that uses a script to rez on object. (I got this to work)
The new object needs the key of the person who steped on the mat. (no idea how to do this)
The new object follows the person who steped on the mat(I can get this to follow me)

Where should I start? any idea where I should look?

Thanks

You can only pass an integer to a rezzed object, and it's difficult (if not impossible) to encode a key into an integer. The way I would do this is to open up a listener in the rezzed object, and have the rezzer tell it the key using chat. So...

In the doormat:

...

integer chatChannel = 98765; // Use any non-zero number, preferably high up

...

llRezObject(.... , chatChannel, ...); // Pass in chatChannel where you pass the integer parameter

...

object_rez(...)
{
    // This gets called when the object has been rezzed. Just to be safe and 
    // protect against lag, sleep a little so the script in the rezzed object
    // gets the time to start running and set up its listener, then tell it the key

    llSleep(0.5);
    llSay(chatChannel, (string)keySavedFromWhenPersonSteppedOnMat);
}

And in the follower/pet thingy:

integer chatHandle;
key keyForFollowerToUse;

on_rez(integer param)
{
    // Param is the chat channel to listen on
   chatHandle = llListen(chatChannel, "", NULL_KEY, "");
}

listen(integer channel, string name, key id, string message)
{
    // The message that comes in is the key
    keyForFollowerToUse = (key)message;

    // Reduce lag, kill the listener since you don't need it any more
    llListenRemove(chatHandle);
}

Edited for typo

Parent forgot the above question.
You can get the key to the person who stepped on the mat by using llDetectedKey in the collision event of the mat. Save it to a global if you want to share it with other event handlers and functions.

collision(integer total)
{
	//Passing 0 gets the key to the first person that stepped on the mat
	gUser=llDetectedKey(0); 
	//do stuff like llRezObject... what the parent said.
}

Thanks for the help, I got it working.

I changed the

integer chatChannel = 98765; // Use any non-zero number, preferably high up
to
integer chatChannel = 98765 + llRound(llFrand(500)); // Use any non-zero number, preferably high up

in the collision call so each Ghost would be on a different channel Probly not neccery, but better safe than sorry

p.s.
I figured out the

gUser=llDetectedKey(0);

But glad to know I did it right

If you have multiple ghosts, that's a good idea.