How can I remap my keys to act like the Macintosh keyboard (like hold alt l + l click = r click)?

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http://askubuntu.com – I want my keyboard layout to act like a Macintosh keyboard. It's hard to use my computer after years on a mac. I want to disable my right mouse click, and replace it with alt + right mouse click. The alt key will also act like ctrl. I want my left ctrl to be the HUD key. I still want my super key to be the same. Can someone please make a script, or point me in the direction of a program to do all this with ease. If you were to make a script/whatever, can you please make one what will reverse all keyboard changes in-case I feel that it is not the same. I will add to the post if I miss any (HowTos)