All I needed was the flight details:

Date
Time
Flight code
Your wifes name (what is on passport)
Your detals, ie name and phone number (so they can contact you if the flight is delayed)

At the top of the form tick, visa on arrival, and then they will take your wife into a room and give her a drink whilst they sort out her visa, take her to get her bags and take her to meet you (or whoever) in arrivals.

I had it when I first came here, it is a veey good service.