[Sony Cross-Device General] LilBlinx:
In this post I’ll explain what is Superuser mod and how to enable it on your device. The Superuser mod disables the nasty signature verification for all apps. After applying this mod you can install apps with different signature like Xperia Z1 or newer Sony apps. Things that are needed in this process are the following:

Rooted device

Deodexed ROM (If you are using ODEXED ROM, just delete services.odex)

Services.jar from your device

Baksmali Manager; the one that I'm currently using and shown in this tutorial

DOWNLOAD

Notepad++

Step 1) Decompile Services.jar file

You can pull the services.jar file via adb or using some file manager on phone. I recommend using ADB since it will be needed for the Baksmali app. Via ADB, type the command:

adb pull /system/framework/services.jar

After you pulled the file successfully copy it and paste it in the baksmali folder. Now, follow the steps on how to decompiling the file.

1. Open baksmali Manager.bat

2. Press 4 (Select file to work) and then press Enter.

3. Enter the number in which services.jar file is shown, in my case it's 3. Press 3 then Enter.

4. After you selected the file, press 1 to Baksmali. Wait until it finishes.

Step 2) Applying the MOD

This is the part we've waiting for, disabling the signature check. Follow the steps.

1. Go to the newly created services folder in the baksmali folder and enter this location; \com\android\server\pm\

2. Search for a file called PackageManagerService.smali and open it with Notepad++

3. Press CTRL+F and search for '.method static compareSignatures'

4. You will see something similar to this:

.method static compareSignatures([Landroid/content/pm/Signature;[Landroid/content/pm/Signature;)I
.registers 9
.parameter "s1"
.parameter "s2"

.prologue
.line 2284
if-nez p0, :cond_8

.line 2285
if-nez p1, :cond_6

const/4 v6, 0x1

.line 2304
:goto_5
return v6

.line 2285
:cond_6
const/4 v6, -0x1

goto :goto_5

.line 2289
:cond_8
if-nez p1, :cond_c

.line 2290
const/4 v6, -0x2

goto :goto_5

.line 2292
:cond_c
new-instance v3, Ljava/util/HashSet;

invoke-direct {v3}, Ljava/util/HashSet;-><init>()V

.line 2293
.local v3, set1:Ljava/util/HashSet;,"Ljava/util/HashSet<Landroid/content/pm/Signature;>;"
move-object v0, p0

.local v0, arr$:[Landroid/content/pm/Signature;
array-length v2, v0

.local v2, len$:I
const/4 v1, 0x0

.local v1, i$:I
:goto_14
if-ge v1, v2, :cond_1e

aget-object v5, v0, v1

.line 2294
.local v5, sig:Landroid/content/pm/Signature;
invoke-virtual {v3, v5}, Ljava/util/HashSet;->add(Ljava/lang/Object;)Z

.line 2293
add-int/lit8 v1, v1, 0x1

goto :goto_14

.line 2296
.end local v5 #sig:Landroid/content/pm/Signature;
:cond_1e
new-instance v4, Ljava/util/HashSet;

invoke-direct {v4}, Ljava/util/HashSet;-><init>()V

.line 2297
.local v4, set2:Ljava/util/HashSet;,"Ljava/util/HashSet<Landroid/content/pm/Signature;>;"
move-object v0, p1

array-length v2, v0

const/4 v1, 0x0

:goto_26
if-ge v1, v2, :cond_30

aget-object v5, v0, v1

.line 2298
.restart local v5 #sig:Landroid/content/pm/Signature;
invoke-virtual {v4, v5}, Ljava/util/HashSet;->add(Ljava/lang/Object;)Z

.line 2297
add-int/lit8 v1, v1, 0x1

goto :goto_26

.line 2301
.end local v5 #sig:Landroid/content/pm/Signature;
:cond_30
invoke-virtual {v3, v4}, Ljava/util/HashSet;->equals(Ljava/lang/Object;)Z

move-result v6

if-eqz v6, :cond_38

.line 2302
const/4 v6, 0x0

goto :goto_5

.line 2304
:cond_38
const/4 v6, -0x3

goto :goto_5
.end method

5. Shrink the whole method so it looks like this:

FOR ANDROID LOWER THAN 4.4 (Donut, GingerBread, IceCreamSandwitch, All JellyBean versions, also there is a chance that will work on some KitKat ROMs if the second method doesn't work)

.method static compareSignatures([Landroid/content/pm/Signature;[Landroid/content/pm/Signature;)I
.registers 9

const/4 v0, 0x0

return v0
.end method

FOR ANDROID HIGHER THAN 4.4 (including LolliPop, KitKat, M)

.method static compareSignatures([Landroid/content/pm/Signature;[Landroid/content/pm/Signature;)I
.locals 11
.param p0, "s1" # [Landroid/content/pm/Signature;
.param p1, "s2" # [Landroid/content/pm/Signature;

.prologue
const/4 v7, 0x0

.line 2934
return v7
.end method

Now find

invoke-static {v4, v0}, Lcom/android/server/pm/PackageManagerService;->compareSignatures([Landroid/content/pm/Signature;[Landroid/content/pm/Signature;)I

move-result v4

if-nez v4, :cond_c

.line 5572
new-instance v4, Lcom/android/server/pm/PackageManagerException;

const/16 v5, -0x13

const-string v11, "Cannot install platform packages to user storage!"

invoke-direct {v4, v5, v11}, Lcom/android/server/pm/PackageManagerException;-><init>(ILjava/lang/String;)V

throw v4

.line 5578
.end local v89 # "s1":[Landroid/content/pm/Signature;
:cond_c

And include do the changes marked in red color

invoke-static {v4, v0}, Lcom/android/server/pm/PackageManagerService;->compareSignatures([Landroid/content/pm/Signature;[Landroid/content/pm/Signature;)I

move-result v4

[COLOR="Red"]if-eqz[/COLOR] v4, :cond_c

.line 5572
new-instance v4, Lcom/android/server/pm/PackageManagerException;

const/16 v5, -0x13

const-string v11, "Cannot install platform packages to user storage!"

invoke-direct {v4, v5, v11}, Lcom/android/server/pm/PackageManagerException;-><init>(ILjava/lang/String;)V

throw v4

.line 5578
.end local v89 # "s1":[Landroid/content/pm/Signature;
:cond_c

6. Save the changes.

Step 3) Recompiling services.jar and pushing it back to system

We've come to the last piece of the puzzle. This is a bit tricky part but I'll make it simple for you, I recommend backing up your services.jar file in case something goes wrong.

1. Open baksmali again and choose services.jar as I previously explained.

2. Press 2 to smali the current work in classes.dex file.

3. In the baksmali folder you will find your services.jar and classes.dex file.

4. Open services.jar file with WinRAR (you can use other software) and replace the new (modified) classes.dex file with the new classes.dex file in the archive.

5. Push the services.jar file using ADB or copy it to system/framework using file manager. The command for adb is:

adb push services.jar /system/framework/

6. Set the permissions to rw- r-- r--

7. Reboot your phone.

8. Enjoy!

Thanks to eybee1970 for making the Xperia T Superuser mod and helping in this awesome tutorial. Also thanks to serajr for the KitKat method