DOOM
Make a directory called \doom\sprites and put the .gif files in
there.  Put hula1.bat and unhula1.bat in your \doom directory.
Type hula1 in your doom directory.  It will make a backup copy of
the imps in \doom\imps.  It will also install the hula imps.
Restart your computer and run doom.  The hula imps will be there! 
To uninstall type unhula1

DOOM2
Make a directory called \doom2\sprites and put the .gif files in
there.  Put hula2.bat and unhula2.bat in your \doom2 directory.
Type hula2 in your doom directory.  It will make a backup copy of
the imps in \doom2\imps.  It will also install the hula imps.
Restart your computer and run doom.  The hula imps will be there!
To uninstall type unhula2 