Now that 56killer has posted the charts to the .ash files i know alot of people are going to be attempting to alter their system menu graphics. So i'm going to give the basic layout to change any file on the wii. This is the method i used to safely make the changes in CSM. Before attempting any changes you need to have preloader installed and get a copy of the .app you are using (42 NTSC or 45 PAL) and the app installer. This is your escape plan if you make a bad change and corrupt your menu.


You will need the following tools. Try to find the appropriate language for you, it makes things alot easier. It MUST be these tools to work properly. This is the only reliable combination i have found.
Adobe Photoshop CS3 or CS4
U8Tool by HowardC - Used to unpack.pack app file
u8Pack 0.8.0 by gally - Used to inject the tpl into the unpacked ash.arc file without unpacking.
TPLConv .4 by by gally - used to inject image files into tpls and select transperancy
ASH.exe by Crediar - used to decompress the ash into ash.arc files.

I'll try to keep this simple and easy to understand. Only change one image at a time, that way if you make any mistakes you'll know what image it was on and you can easily fix or undo it.

Copy the 4x.app file that you obtained into a new empty directory
Run U8tool Next to the entry for Archive file Click the ... box to enter file selection menu. Select your 4x.app
Click the lower left button marked extract. Wait Awhile... Quite Awhile.... I'm not kidding. No its not frozen.. its just slow... No you can't use something else to do this part, they don't do it properly. It can take up to two hours, since it can only see one processor and one thread Don't worry packing only takes 20 seconds.
Once it finally finishes unpacking copy the 00000004x_app_out directory to somewhere for safe keeping, so if you mess up badly you never have to extract that again. you could even rar or zip up a copy of the directory if you want.
Using 56killers ash guidechart find the image you want to change.
Copy Ash.exe into the 000004x_app_OUT\layout\common directory
Drag the ash file that contains the images you wish to change onto ash.exe, or from a command prompt in the current directory just run ash.exe
This will output a .ash.arc you can now delete the original .ash
Rename the .ash.arc file to .ash
delete the ash.exe copy from the common directory
Thanks to how 56killer has made his charts we can use them to our advantage and skip several tedious steps.
Right click on the image on 56killers post and select save image as, then save the image as it is named it will be a bmp
Open this bmp in Photoshop CS3 or CS4.
Make the changes to it that you want to take effect, but you cannot change the size of the image. If it is an image with a transparency it is best to use the color the original images use for transparent areas, you can get away with other colors, but on some images it causes the rest of the screen to go distorted. Save your image as a 32 bit bmp no alpha layers.
(Note: Some images like the cursor have their own secondary and third images that are used for alpha transperancies and color blends)
Run tpl conv by gally.
Select Read image and then select the bmp you just saved.
If your image has a transparent color then select RGB5A3 and click on the color that is supposed to be transparent.
If your image does not have any transparent sections then select RGB565.
Click Save TPL
Save the TPL with the name of the original image (example my_ComBtn_d.jpeg.bmp would be saved as my_ComBtn_d.tpl)
Close TPLConv
Run U8Pack by gally
Select Open Archive and open the ash file that you decompressed (in example about that would be board.ash)
You will get a directory and file listing showing the contents of the ash file. Scroll down to the timg directory and find and select the file you are replacing. They must be named identically.
Now click add file and select the tpl you created with tplconv.
It should prompt you to overwrite the file, if it doesn't exit the program, check your file naming and start u8pack from the beginning. If it does ask tell it yes. Then select create archive select the original .ash file you opened and hit save after a moment a box pops up confirming the file was created.
Close any programs open from earlier steps.
Run U8Tool this time choose the ... box next to archive folder and select the 000004x_app_OUT directory
the only things selected should be delete any recursive "_out" folders before packing and regular archive header. anything else will cause corruption of system menu. Archive file should automatically fill out as 0000004x.app in the directory containing 000004x_app_OUT
Press Pack... wait up to a minute. a box will pop up saying the app was created.
Copy the app to sd and install with your prefered app installer.
Reboot system.
Enjoy change or make adjustments. If you want the original back just copy the original 4x.app i told you to put somewhere safe to sd and install it via app installer.
Hope everyone can follow that. i've been sick the last 5 days now, meant to put this up sooner.

Note you can use yaz0enc.exe to encode the .ash files and reduce their size to almost normal.

I'll write up an advanced tutorial on the css/html/animation/sound changes later unless someone beats me to it.