You will need a receiver wrench and a barrel vice. Both must fit properly. Even with the correct tools, the original barrel may not be easily removed, and you will have to deal with this without damaging the receiver.
You will need a replacement barrel, and have the tools to adjust the fit if necessary. No. 4 barrels usually require less adjustment than SMLEs.
You will need headspace gauges, and will need to be able to adjust headspace if necessary.
As far as degree of difficulty goes, easier than some, more difficult than others. With the correct tools, certainly possible.