Unfortunately, the application doesn't have a Mac version and there is no way for you to run iPad apps on your MacBook Pro. However, if you really want to have it on your Mac, there's an alternative solution that you can try, but it requires a bit of extra effort:
First, install either WineBottler or Boot Camp on your Mac, then use one of those emulators to install the Windows version of Gamin GTN Trainer. I can't guarantee that it will work, but it's definitely worth a shot if you're up for it.
