Yea I've had problems with all kinds of mods and packs but I've worked out a system that while may be in the extreme, seems to work for me every time. Also, I'm on Windows 7 PC, I know diddly-squat about Mac's and plan to keep it that way, any followers of Jobs are on their own...
Start by downloading the Mods or texture packs you want to install and keep a window handy with those files for use in a few minutes...
Next locate your --> %appdata%\.minecraft <-- folder. You can simply type this into a run command and it will open a separate window...
Now, if you care about your single player games and maps you will want to find the saves folder within .minecraft, and copy it somewhere. Drag it to your desktop, put it in your downloads folder, doesn't matter so long as you remember where you put it.
Once your saves are safely tucked away, delete the .mincraft folder and relaunch minecraft to allow the current version to download and start with a clean install.
Open the mod/tex pack you wish to install, should be a .rar or .zip, in this case I will use AaGeOn's 128 bit pack as the example, drag the contents of the mod/texture file to your new \.minecraft\ folder.
NOTE: Sometimes mods need to go in the \.minecraft\bin folder sometimes only to the \.minecraft\. Check the first post of the thread where you got the mod/tex pack also take a look at the readme file from within the download for specifics...
AaGeOn's simply has a bumpmaftxxxx.jar file and the mcpatcherxxxx.exe file that are required to get this to work...
From within the .minecraft folder double click on the mcpatcher file. It will create a backup file of it's own (minecraft.original.jar) and should have both the Original & Output files filled in, in the patcher window.
NOTE: This can be confusing as the Original is not your file, it's actually the 'backup' that was created by the patcher. The Output file is (minecraft.jar) which will be the 'new' file created to run minecraft.
Ex:
Original - C:\Users\AppData\Roaming\.minecraft\bin\minecraft.original.jar
Output - C:\Users\AppData\Roaming\.minecraft\bin\minecraft.jar
Click the Browse button on the right side of the Texture Pack line and find that bumpmaftxxxx.jar file, which should be in your \.minecraft\ folder, something like this ...
Texture pack - C:\Users\AppData\Roaming\.minecraft\bumpmaft v1_4.jar
Once the texture jar file has been selected the patcher should auto fill in the check mark and change the tile size to 128x128.
Choose all the options you want to install.. In my case I checked them all .. Then click Patch.
A little java script window will run once you get a 'hopefully successful' type message close all the windows and enjoy your new 128 bit texture pack.
Running other mods is similar just be aware of where the files need to go in either /minecraft or /minecraft/bin.. or other.. Also the order you install sometimes has effect on one or more mod so be aware of conflicts.. If more than one mod has a minimap or chat feature you will likely run into conflicts..
