Problem :
I'm a Samsung galaxy mini user and i have a doubt. My doubt is that when i installed cyanogen mod 7 on my galaxy mini, Samsung launcher has been replaced by zeam launcher and I'm not able to uninstall it. So, is there any way in which i can replace zeam launcher by some other launcher like Sony Ericsson and make it permanent. (uninstallable).

Solution :
Yes, it's possible to replace the default launcher app. By using a root app called Root Explorer you can do so instantly and easily by following the detailed instructions given below. So, before you follow the steps below, Make sure you have Root Explorer installed on your CyanogenMod 7 rom.

• Get yourself the apk install file of the new launcher app that you are going to replace with the default one and copy it to your sd-card.
• Now, Browse to /system/app/ folder using Root Explorer and mount it as read-write from the mount R/W button present at the top of the app.
• Now copy the new launcher app to system/app/ directory, which is where you can find all system applications.
• Once you are inside the system applications directory ,search for the default launcher app and rename it to add .bak at the end of it's name. [See example below.]
• Now, rename the new launcher you copied earlier with the name of the default launcher app.
• Once done, long press on the new launcher file to get a list of menu options. Select Permissions from the menu (you should see something like below --not exactly the same though.)Then, Set appropriate permissions : Read-write for Owner and Read only for Group and Others. Or more specifically, set permission to rw-r-r. You can also use root explorer permission option to set the permission as shown below :

Permissions for System Applications

• That's all. Now reboot your device and your android launcher should now be replaced with your favorite Home launcher application.

In case if you find the above steps confusing, you can try adb commands to replace default launcher by pushing new launcher as the default launcher and settings appropriate permissions using chmod command of busybox.

However, to better understand the case above, I will present a simple example. Assume your default Launcher name in system/app/ directory is ADWLauncher.apk and you want to replace it with a new launcher be it Xperia Launcher.apk. Now, you copy this Xperia Launcher.apk to system/app/ directory and rename ADWLauncher.apk to ADWLauncher.apk.bak [We do this so that we can use it later on in case we run into problems.] Now, rename the new launcher (Xperia Launcher.apk) to ADWLauncher.apk
and set permissions as rw-r-r (as shown in the diagram above). Now, reboot your device and see the changes take effect.

That's all to replacing default android home app with whichever launcher you have to make it permanent. You can alternatively install the new launcher and set it as default one in Manage Applications settings too. Do let me know if you have any doubts at the comments below.