This is also not possible.
What happens when you are trying to installing Skype?
Did you receive any error code / messages?
I don't know if this will help but if you're installing Skype on Windows 8 from the download section you have to be using Internet Explorer to be able to click the download link since it's technically an app. I'm a Chrome guy and I was sitting there for a good 10 minutes trying to figure out why it would work.
Much like the original poster, I too require push-to-talk. If you think you'll need any options at all you'll want to download the desktop version.