You can install modloadler and another mod that requires modloader at the same time, follow the simple steps below
Download Risugami’s Modloader if you haven’t already. link:
http://www.minecraftforum.net/topic/75440-v125-risugamis-mods-everything-updated/
Open up the Minecraft folder following one of the following 3 steps, depending on your OS (operating system).
- In Windows XP: Click on the Start button, and then click on Run. Type%appdata% and click Ok. Minecraft should be the first folder. Open it.
- In Windows Vista/7: Click on the Start (Windows) button and type%appdata% in the search bar.
- In Linux Ubuntu (should be the same on other Linux Distributions):Open up your Home folder. Look for the Minecraft folder. (Note if you cannot see this folder, enable “Show Hidden Files. When you find it open Minecraft.
Open Bin folder.
Open the minecraft.jar file with 7zip or similar.
Drag the .class files from the Modloader folder into the .jar.
Delete Meta-inf, close the .jar and run Minecraft.exe.
Log in like normal. ModLoader is installed!
Note
To install [most] mods, use the same method. ModLoader is required for some mods.
If you delete anything other than the Meta-inf folder, just delete the Bin folder and log in to Minecraft again. Unfortunately, you have to reinstall the mods again.