bcdedit.exe /set nx OptIn = “Turn on DEP for essential Windows programs and services only”
bcdedit.exe /set ns OptOut = “Turn on DEP for all programs and services except those I select”
bcdedit.exe /enum = Query Settings
bcdedit.exe /set nx AlwaysOff = “Disable DEP entirely”

To disable DEP just to internet Explorer 8 – see this article
http://blogs.msdn.com/b/askie/archive/2009/07/02/how-to-disable-dep-ns-memory-protection-in-ie-8-via-policy.aspx

References:
http://msdn.microsoft.com/en-us/library/windows/hardware/ff542202(v=vs.85).aspx