If you want to scale an object, or a group of objects, or the whole DWG drawing with different (independent) values of X-, Y- and Z-scales, you can use blocks.
Non-uniform scaling (resizing) can be done by enclosing the scaled entities into a block and then reinserting this block in a non-uniform scale (X/Y/Z).
Use the BLOCK command to make a block from the entities you want to resize. Then use INSERT to bring these objects back. You can enter different scale factors when specifiying X, Y and Z scales for the block insertion (reference).
You can also use a combination of the COPYBASE and PASTEBLOCK commands and change the X-Y-Z scales of the pasted block in the Properties palette (Ctrl+1).
In any case, use EXPLODE the inserted non-uniform block back into the individual entities.
You can automate the non-uniform scaling process with the free ScaleXYZ Lisp utility available on www.cadstudio.cz/download. It contains the commands ScaleX, ScaleY, ScaleZ to scale entities in the individual directions.