Extracting texture

I would like to know which is the best way to extract a part of a texture as another texture, like repeating a smaller portion of an image. Thanks for any replies.

draw the texture into a renderer, and use DX9Texture to use the content of the renderer as the texture of an object in a second renderer. rinse and repeat.

or maybe read on applying transformations to textures in HowTo DX Rendering under Texturing