AccessControl::DisableFileInheritance "$temp\test.tmp"
Pop $0
DetailPrint $0
AccessControl::ClearOnFile "$temp\test.tmp" "(S-1-5-18)" "FullAccess"
Pop $0
DetailPrint $0
AccessControl::SetOnFile "$temp\test.tmp" "(S-1-5-32-544)" "FullAccess"
Pop $0
DetailPrint $0
This might not be enough, you should probably also use SetFileOwner and maybe SetFileGroup...