Many information technology project managers come from senior technichal positions. What can you do to help them transition into a project management role?

The best way that I can think of to help someone transition to a project management role from a senior technical position would be to assist them from a kind of background support role. The idea would be that you would help by working to get the support of your fellow team members and to suggest practices and methodologies that you know to work. The suggestion part is important, never back someone into a corner,  if they feel that they don't have a choice about it then that will build resentment which will not only make the goal of assisting them to transition to the new role harder, but will also probably prompt them to try to make your life miserable any time you have to work with them. The other side of this is that you can't help too much. You have to know when not to interfere with a situation. If they become too reliant on you to fix their mistakes, regardless of whether they know they are or not, then they will never learn how to lead a project by themselves and will fail as soon as they no longer have you to use as a crutch.

In short, to help someone transition from a technical position to a project management role; be subtle with your help, don't try to take over the project, and don't try to fix their mistakes.