You can not run a single method as administrator. However, you can impersonate a user that has administrator rights at the start of the method, execute some code as the other user and then go back to the original user.
The accepted answer to the following question lists some options: How do you do Impersonation in .NET?
In his answer to the above linked question, Matt Johnson also shows some code to do it hassle free, which he obviously also posted as a DLL to GitHub, where you can download and use it.