Changing oil pressure dial?

[MKH9130]

I have a '96 MX5 with the 'on-off' oil pressure gauge. I'd like to change it for the proper gauge from the earlier cars, is this difficult to do?

What bits do I need?

[Munter]

I think you want these instructions. I thought about doing it. Then decided I couldn't be bothered.
http://www.miata.net/garage/opg.html