If your TV has a SCART RGB in, it can directly replace it, but a cable or adapter would need to be made.   RGB SCART actually turns the TV into an arcade monitor!
  If it only has component, S-Video, Composite, or RF inputs, you would need some sort of an NTSC (or PAL) encoder that can output a signal compatible with the TVs inputs.   Using Component in this case is best, with S-video in second place in terms of output quality.   Composite and RF often results in very low picture quality.