It's possible to make your own tile set for Lemmini and its corresponding 'styles' for Lemmix in your favourite image editor (e.g. paint) and save as (name(suffix)_x).GIF as I am doing now.
Edit:
The main problem that I am having at the minute is the 'magic colour' for the transparent sections on 'non-square' tiles. Any ideas?Nevermind, my problem is solved.
If you really want to make your own tile set, look here: -
http://lemmingsheaven.info/forum/index.php?topic=5.0
