I'm not sure how the LNP works, it includes lots of weird hacks and utilities.
For the tiles, you:
- put the character tile images in /data/art in either .bmp or .png format
- edit /data/init/init.txt to point to the files you just saved, similar to this:
[WINDOWEDX:80]
[WINDOWEDY:25]
[FONT:GuybrushASCII_curses_square_16x16.png]
[FULLSCREENX:0]
[FULLSCREENY:0]
[FULLFONT:GuybrushASCII_curses_square_16x16.png]
[GRAPHICS:YES]
[GRAPHICS_WINDOWEDX:0]
[GRAPHICS_WINDOWEDY:0]
[GRAPHICS_FONT:GuybrushASCII_curses_square_16x16.png]
[GRAPHICS_FULLSCREENX:0]
[GRAPHICS_FULLSCREENY:0]
[GRAPHICS_FULLFONT:GuybrushASCII_curses_square_16x16.png]
[GRAPHICS_BLACK_SPACE:YES]
For the graphics, take your desired dwarf / creature graphics pack and replace everything that is in /raw/graphics.
As long as you set the [GRAPHICS:YES] flag in the previous step, you'll be ready to go.
But, since you're using LNP, I'm not sure that following these instructions won't break something. It hacks the game in strange ways, and I'm not sure how it works.
Some of the fancier graphics sets come with seperate true-type fonts, bundle Character Sets and Graphics Sets together, and include extensive edits of the RAWs (game data) to change the default icons that various objects use. I find all this to be very confusing and I think has far too much that can go wrong.
So I stick to the simple stuff.