I was about to answer this question when I realised I had a problem.
If I want to say "Please do A or B" where the actions involve different verbs then, hopefully:
Please either go to the shop or use the internet to buy the book.
is a grammatical -- and hopefully natural -- sentence.
So if I wanted to say "You can do A or B" it seems like a natural extension to write:
To buy a book you can either go to a shop or use the internet.
But the internet has a disturbing lack of text that contains どちらか出来ます, so I'm guessing that this is, at best, unnatural and maybe ungrammatical too.
If it is unnatural what is the correct way to express that you have the ability to do one thing or another thing (but not necessarily both)?