I have seen some questions about texture alignment and patches in other threads. I have written down some information here, that could be useful to others too.
I assume you are capable of editing brushes and patches, and you have some knowledge about vertex (V) and edge (E) editing. You also have to know how to fit textures on a brush and, obviously, how to select brushes, surfaces and patches. I use radiant 1.5.
We start with two brushes of the same size and a patch in between. I've textured them with
atcs/eq2_trimv_02. Make sure the texture fits the brushes: either resize the brush until the texture fits, or use the
Surface Inspector (S) to make it fit. Do not touch the texture settings of the patch.

This doesn't really look as it should. Select the patch and open the
Surface Inspector (S). Click the Set button and the
Patch texture layout menu opens. Here you can specify how many times the texture has to fit on the patch. Enter an x-value of 2 and an y value of 1. If your patch is rotated you might have to swap the values.

This looks much better:

Now we'll create a curved wall. Activate the
Texture Lock with Shift-T or the lock icon in the toolbar. This will keep the textures locked on brushes as we move them. Move the right brush up and deform the patch to create a curve:

Note the texture on the patch follows the curve nicely. This is because of the texture settings we made in the
Patch texture layout.
(disable texture lock again)
Now we make the right brush higher and deform the patch accordingly:

The texture size on the brush hasn't changed so it is repeated as expected. The texture on the patch on the other hand, has a fixed size set and follows the curve of the patch.
There are two ways to fix this: either resize the texture on the right brush with the
Surface Inspector, or change the texture settings on the patch. You can do this by selecting the patch and pressing the CAP button in the
Surface Inspector. You have to click CAP multiple times to cycle through the available CAP styles.

Useful keys:
shift-arrows: shift texture
ctrl-arrows: scale texture
shift-pgup/pgdn: rotate texture
ctrl+c: copy texture
ctrl+v: paste texture
Try the Fit button in the
Surface Inspector, in many cases it will do what you want.