Is it possible in Photoshop to convert slices into photoshop layers?

You can do this all using Javascript. Here's a quick little script I've written, it will copy your image into 100 layers, each 10px by 10px:

/*
--------Photoshop Script - Grid to Layers------------
Author: Oisin Conolly
        www.DigitalBiscuits.co.uk

This basic script will create new layers from your active layer, each equal in size according to the grid dimensions specified.
*/


//this is the size of our squares in pixels
var squareSize = 10;



var docRef = app.activeDocument;

//set the ruler type
if (app.preferences.rulerUnits != Units.PIXELS)
{
    app.preferences.rulerUnits = Units.PIXELS;
}

var layerRef = docRef.activeLayer;

for (y = 0; y<docRef.height; y+=squareSize)
{
    for (x = 0; x<docRef.width; x+=squareSize)
    {
        //activate the original layer
        docRef.activeLayer = layerRef;
        //make the selection
        docRef.selection.select(Array (Array(x, y), Array(x, y+squareSize), Array(x+squareSize,y+squareSize), Array(x+squareSize,y)), SelectionType.REPLACE, 0, false);
    
        //copy the selection
        docRef.selection.copy();
        //create and paste new layer
        docRef.artLayers.add();
        docRef.paste();
    }
}

To use it, save that file and load it up with Photoshop by going to

File > Scripts > Browse

Make sure the filetype is set to *.JS

If you want to change the size of your squares just open the JavaSCript file in Notepad, change the value for squareSize and save and run it.

Also, if you want to do more advanced things with this script, you can download a Photoshop Scripting reference guide which lists all the classes, functions and variables you can work with. (For example how to rotate a layer).

The above script uses JavaScript syntax, however you can also use AppleScript, and VBScript to work with Photoshop.