I don't use dragon, so i can't help you. But heres how you do it with map generator, might be helpful.
Step 1: patch the artwork to your verdata if not already done.
Step 2: fine Terrain.xml in your data folder
Step 3: Add your new tile in there
Quote:
Any number can be hex if preceeded by a 0x. The ImgIndex is the index into the
palette that will be used. The tile is the tileid in UO. The name represents
what one wants to refer to this by (meaningful as it will be used for any paint
program swatch file).
BaseAltIndex represents the index id for the altitude. It will use that altitude
as a reference point when creating the altitude image file.
Adjust represents if one wants to reandomly alter the altitude. If present,
the frist two numbers are the mininim and maximum one should adjust.
The third number is optional, and represents the step size to move from the minimum
to maximum. It defaults to 1.
Red, Green, and Blue represent the color component values (0-255) that make up the
color channels.
The attributes can be any order.
Step 4: Open up paint, and add the color you selected to represent your new tile into your swatches.