Before we get started this is not my solution all credits are for Aether.

Ok, first of you need to download the Xcode.app from the Mac Store. It's 3,19Gb so it takes some time to download. I've download it in my Notebook and the copy the installer to my other PC. (I'm a Hackintosh user)

UPDATED! WORKS WITH 10.8 MOUNTAIN LION

So let's start:

1- After download completes, execute the "Install Xcode.app" and follow the installation.

New steps!

1A- Run the downloaded app and install XCode.

1B- Open XCode and go to Preferences > Downloads > Components and install the Command line tools.

(on previous versions the command line tools were installed with the main program now you need to manually install them.)

Thanks to m3tz for the tip.

2- Install your Maya 2012, I used the Maya 2012 Hotfix 4 downloaded from Autodesk website.

3- After Maya install disconnect from internet (not sure if it's needed but it wont hurt)

4- Download the activator from Aether first post. Expand it and copy it to your user's root folder.

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5- Run Maya 2012. Follow the activation till this point.

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6- Run the Activity Monitor in Utilities. Make sure it shows All Processes. Now locate the "Autodesk License Management Utility" and take note of the PID number next to it.

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7- Open a Terminal Windows and maximize it, this is important ! do it! Now enter the following line:

vmmap -resident -interleaved PID

PID is the number next to the Autodesk License…..

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8- Now use the Command+F to search the Terminal Window and paste this "libadlmact_libFNP.dylib". Copy the hexadecimal base address of the __TEXT segment. We need the first 8 digits.

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9-Now open a new Terminal Window and enter the following code:

sudo gdb adesk.app/Contents/MacOS/x-force

This will work as long as you put the adesk.app in your User root folder.You'll see some like this.

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10- Enter this into the Terminal Window.

b *0x32c2

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11- Now enter "r" into the terminal and hit return. This will run the adesk activation program.

12- Copy your request code from the Maya activation window and request your activation code. Enter it into the Maya activation window. And finally it the MEMPATCH button.

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13- Back into Terminal. Enter:

p/x $eax

You should get something like this

14- The final step for get the MemPatch to work is to enter this into terminal.

set $eax=0xADDRESS

Where the address is the 8 digit number we get from the other terminal window.

Hit return.

Now type "c" and hit return. You should see the MemPatch Success window.

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15- Hit next in the Maya activation and you should see the License active window.

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Done it in two Lion installations without a problem.

Good Luck

Copypasta from: http://forum.cgpersia.com/f37/maya-2012-lion-fix-37130/#ixzz277CdweR2