It sounds to me like you used the CD version of TurboTax all those years. If so, the CD version for each individual year contains both the MAC and Windows version of the software. So using the CD for each individual year, install each year of the program on the MAC.
Once installed, you will need to transfer over the appropriate .tx201x files from your windows computer to the MAC computer. You should be able to do this using a thumb drive. On the windows computer the files are located in the Documents\TurboTax folder. Unfortunately, I do not know where to transfer them "TO" on the MAC.
