The short answer is Federal EIN will work for registration with the Indiana state revenue department.
An employer who has even one employee residing in Indiana state and working remotely from there will require withholding of state taxes on the pages. That requires registration with the Indiana Revenue department, which is done online .
In order to register for withholding for Indiana, the business must have an Employer Identification Number (EIN) from the federal government. You can Register your business with INTIME, an information management engine for Indiana taxpayers.