Spelling mistakes in published conference paper at IEEE Xplore
It may be impossible to get a change made, but a possible approach would be to contact the program chair of the conference (or the conference chair if necessary) and ask for advice. They will know what is possible and what is not. 

But it is also likely that the errors are merely a nuisance and not fatal to the work. It hasn't been a long time, yet, but over a longer period things get harder to change and more likely to be ignored. 

Print versions are quite unlikely to be changed for anything but books that go through multiple printings with some editor intervention between printings.