If you would like to have some random carved stone heads on the four side faces of a block and random rune carved slab top and bottom faces (using MC Patcher's CTM facility), drop the included files here into the ctm folder in the zip pack:

Glimchiseledhead.png
terrain225.properties
Glimcarvedslab.png
block35.properties

This will alter the light grey wool block. 

To use with another block of your choice, you will need to edit the above .properties files to address the 'terrain' or 'block' id and metadata of choice (info on that subject is available on the Minecraft wiki).