Newbie question on changing reg keys

We have been asked to add/change a registry key on our servers by the vendor of an application we use named BrokerApp

The key is

[HKLM\SYSTEM\CurrentControlSet\Services\BrokerApp\parameters\logon]

The value is "debug" = "1"

Some servers don't have this key at all, others have debug set to 0

We have 70 servers we need to roll this out to, all Windows 2008.

What's the quickest way to do this, either via Powershell or otherwise?

Ideally, what I'd like to do is:

1. Save the existing reg to C:\Saved\REG
2. Make the change above

Also, if possible, run a script that would comepare the original reg to the changed one to ensure thatthe only thing changes is the BrokerApp logon debug. Is this all possible via Powershell, and could someone help me get started? Not looking for the answer here, just a way to kick it of.f