Can I get a sport pilot license while taking Mirapex?
Assuming you have never applied for a medical certificate:

You need to ask your doctor. Sport pilots don't need to have a medical certificate, but they do need to be capable of operating an airplane safely. Mirapex is on the do not issue, do not fly list, so the presumption is that you cannot fly while taking it. In order to legally fly solo or with passengers while taking Mirapex, your doctor must tell you that it's safe to do so.

Your doctor may tell you that it's not safe to fly while taking Mirapex. In that case, you only have two options: stop taking the medication (with the approval and supervision of your doctor), or don't fly (except as a student receiving instruction). 

If you have applied for a medical certificate ever in your life: You need to get a medical certificate in order to fly solo or with passengers. In this case, you need to talk to an aviation medical examiner for advice; there's no way around this.