Here's the info from the last question found on the tour FAQ page...
Q - How can I purchase tickets for disabled access?
A - In North America you can click the accessible seating icon on the 'event detail' page, and fill out a form, which sends an email request toTicketmaster's e-care for handling. The form contains a field to accept your access code. If you are booking tickets for European shows and you requirespecial needs seating please follow the instructions on the relevant page of the website that is selling the tickets for the show of your choice.
Hope that helps