Adding a Mosaic Tifo

Here is how to add a general texture on the multiples signboards to form a picture.
This tutorial assumes that your entities already contains a signboard if not please refer to the How To Add Props tutorial in order to understand how to add some new geometry to your Golaem Character. (doing so do not forget to correctly tile your UVs! ;)
1. Create a basic geometry to generate your crowds on. Assuming that the entities are going to be generated inside each faces keep in mind the number of rows and columns.
2. Create a UV offset texture  based on the length and width of your grid placement.
Here is mel script to do so:
writePpmUvFile("C:/test15.ppm", 15, 15);
// 15, 15 being the values of length and width you may change it to your will
// code
global proc writePpmUvFile(string $filePath, int $length, int $width)
    if ($length > 256 || $width > 256) { error("Too big!!"); return; }
    string $fileContent;
    // header
    $fileContent += "P3\n"; // magic word
    $fileContent += ($length + " " + $width + "\n"); // length / height
    $fileContent += "255\n"; // max value
    // content
    int $colorIndex=0;
    for ($iL=$length-1; $iL>=0; $iL--)
        for ($iW=0; $iW<$width; $iW++)
            int $r = $iW;
            int $g = $iL;
            int $b = 0;
            $fileContent += ($r + " " + $g + " " + $b + "  ");
        $fileContent += "\n";
    // write file content
    $fileId = `fopen $filePath "w"`;  
    fprint $fileId ($fileContent);   
    fclose $fileId ; 
3. Once this .ppm texture is created , convert it in png for example into your favorite image editor.
4. Load the texture in your scene by selecting your placement geometry and creating a Paint Trigger Zone .
5. Place the crowd by selecting the faces and using the Population Tool  option "Create particles on selected component" .
6. To store the Id of your particles to offset the picture in your signboards create 2 ppAttributes in the crowd particles shape and name it "offsetYPP" and "offsetXPP".
7. In your shader scene create a shader for the signboards, using the maya 2D file texture connected to the shader color attribute. Be sure to map this shader to your Golaem character by going in the Character Maker geometry tab and clicking the reset shader button (save your gcha). 
Notice: the placement of the texture depends on the UVs of your signboard, check the UVs and adjust the placement with the Place2d texture's coverage and Offset.
8. Add two getUserdata shaders and link them to the placement2dnode U & V offsets (if using V-Ray do not forget that it is the outalpha that you need to link to the placement2dnode). This will enable you to control the U & V offset of the texture applied to a particular tile with the offsetX and offsetY ppAttributes. See this tutorial to learn how to feed the getUserData shader with ppAttributes values.
9. Go to the Geometry Tab in the Character Maker, find the shader assigned to your signboard and add two float Shader attributes to allow it to perform the uv offset: offsetX and offsetY. You can also use the Reset Shaders button  after selecting the signboard Mesh Asset node. This will add the Shader Attribute nodes automatically. Tick the box to use the ppAttribute of your particles