Do you have a link to the blog?
Instead of using a plug in module, he may have used a hack module, inside the case of the original module. They're a bit too big to fit in a more modern 5 pin module, but should fit in the bigger, older modules. If not, cut a hole in one side and let it occupy some space inside the case, I guess.
The connectors that are used on some Arduino shield boards are a good fit to the pins, and there are right angled versions, e.g. ones made by Truconnect. I used one to repair one of my FrSky modules that had a bad connector.
One of this range of connectors is suitable, and you can cut them down, though there are some 5 pin ones:
I expect those are sold internationally.
The hack module looks like this
They're normally installed by soldering, but you could use one of those connectors to push fit onto the module pins instead. They're better quality than the ones that FrSky uses in it's push fit modules.
The main advantage of the hack module is tidiness. The antenna is separate so you mount it where you want it, and all you need is a small cut out somewhere (e.g. in the back of an old module) for the LED and button. If it's inside an old module case, you'll need a cut out to run the antenna through into the main case too. The coax for the antenna has a screw on connector where it attaches to the antenna. A hole big enough to fit your little finger (pinky) through is enough to route the cable, and you need something like a 1/4" hole to mount it, where the antenna goes.
There's a telemetry version of the hack module too, which has a mode switch. Apparently that switch goes wrong after a while, so I prefer the simpler version. FrSky design and electronics good. FrSky connectors and switches bad
The alternative would be to just solder it in whichever mode you use. If you're buying all new gear, that shouldn't be a problem.
There are only three connections to make to a FrSky plug in or hack module, so it's quite simple. You just need ground, switched power and PPM. Once you know where to connect those three things, the rest is just mechanics.