I download a copy of each fabric image that I want. I will usually download several of the same fabric if there is any kind of complex pattern on it, because I can't make a seamless tile out of something with just a portion of the pattern, and if I can get several that each have a part of the pattern, I can piece them together into a single pattern.

So, with my fabric images in hand, I take them into PSP (I have version 8.1) and I select one that I want to work with.  I increase the canvas size to about 1000 x 1000 and decrease the colors to 16.  I save the palette and make a note of the RGB information for each of the colors as well as the color index information.

Then, I make a copies of the other fabrics with the same pattern, decrease their colors to 16 also, and save their palettes as well.  Then, I take those copies and play with the color indices until they are the same color and have the same feel as my starter image.

Now, I can cut and paste them into a complete pattern.  When I have enough material pasted together to have a large enough section for a single repeat, then I merge my layers and save the result as a tile.  I can then take that tile back into PSP and save it as a texture which I can then just paint into my UV maps (and distort  and resize as necessary) to create fabrics.

For example, I found a really nice brocade at the site, and took the blue, red, and brown jpgs to work with.  Made them into a single repeat tile, and then took that tile, recolored it as needed (with only 16 colors to work with that part is really easy), and mapped it to the latest (not quite finished) version of the ballgown.

She's going to be sort of a "Miss Scarlet" kind of character, so I still need to model a nice wide bonnet for her ..... but you can see how the green brocade fabric works.

Working with plaids and some other types of fabrics is much easier simply because getting to the point where you have one repeat is a piece of cake.

Could be worse, could be raining.