I was there at the end of October. I went to the MyFone store close to Taipei 101. It's on one of the main roads in shopping mall/movie theater.

Eventually they found some one who spoke enough English to help me. They had a card with a number of different options and plans. I ended up with a SIM that had a reasonable amount of data and I think some small amount of talk time. I don't recall if it was good for 10 days or 30 days. But I believe I paid NT300 or maybe 500. I thought it was a good deal. Great high speed coverage. Google maps came in very handy on more than one occasion. Good service down around Tainan, Sun Moon Lake area and in Lukang as well.

Only needed my passport which they made a copy of and I think I had to fill out a form. They installed the card and activated everything so I was good to go by the time I left the store. I was recommended to go there by a friend who suggested that there would be a better chance of them being used to dealing with foreigners.

It's too bad it's all so complicated.