That DIY is about installing an aftermarket sunroof and is not recommended until and unless done by a highly skilled professional.
Nowadays people normally install the same model original sunroof which is done in a rather simpler way.
All you need to purchase an old complete roof fitted with a sunroof mechanism, such roofs are available in the junk market of your city for around 40 to 50k that includes inner roof trim, handles, roof light and complete wiring along with the operating switch.
The procedure involves removing both rear and back glass screens then the roof weather strips are removed, beneath these strips there are number of spot welding joints. The mechanic first break all these weld joints and replace the existing roof with the new one, afterwards the new roof is painted to match the color of the car. In some cases this last step is not required if you are able to find a similar color roof.
Good workshops have spot welding machines and normally they do work on such projects.