To install them, you only need Java (you already have this if you are playing the game), and a compression tool that supports .JAR files (I use 7zip found here).

Download the zip below:
http://www.lostpower.com/files/Def-Textures.zip

Extract all the files to your desktop (or somewhere similar).

Open your minecraft BIN folder.

If you are on Windows XP, the bin folder is at:
Cocuments and SettingsUSERPROFILEApplication Data.minecraftbin

If you are on Windows 7, the bin folder is at:
C:UsersUSERPROFILEAppDataRoaming.minecraftbin

Note: USERPROFILE is the user you are currently logged in as.

Once you have that folder open, right click on the minecraft.jar file and open it with your compression tool.
If you use 7zip, you would right click, then choose 7zip, and then Open Archive.

This will open the JAR file and show you the contents.

Now go to where you unpacked the ZIP file you downloaded earlier and open the DEF-DOKU-TEXTURE folder.
Select all files and folders in this folder (CTRL + A), and then DRAG the files/folders to the open minecraft.jar Archive.
It will ask you if you want to add these files to the archive (it may ask if you want to overwrite the other files), just choose Yes.

Once you got the files added, close the minecraft.jar archive.

Go back to the folder on your desktop, and double click on jarfix.exe.
You should get a message telling you that the java extension has been registered.

Once that is done, copy the mcpatcher-1.1.7.exe from the current folder to your .minecraftbin folder.

Now double click on the mcpatcher-1.1.7.exe file from your .minecraftbin folder.
Turn Tile Size to 32x32 and turn on all the animated stuff, then click Apply Patch.

Click OK, and you're done. You should now have the updated DOKU 32x32 textures, but with normal glass and moving waterlava.