It's not a terribly hard job as it really comes down to removing the brifters completely and doing a new install on both the TT bar end shifters and the much simpler brake levers.
The gotcha's are that you will likely have to replace the brake cables and housings, shifter cables and housings or both. In fact you'll almost certainly want to use new cables both because cables should be replaced from time to time and it's a good opportunity and because rethreading a previously used cable that's kinked by the clamping bolt (on the brake or derailleur end) or frayed and unraveling can be a major PITA and new cables themselves only cost a few bucks. Well, maybe you can reuse the cables - but, why? I would get new cables - even more so if the housing is not a full housing. What can happen is that there is some oxidation on exposed parts of the cable and then it ends up in housing and is stiff from the friction of the oxidation.
The brake cable housings may work out just right in terms of length assuming you're going to use the same handlebars and a similar design of brake (e.g. hidden brake cables on the new brake levers). If you're swapping from road drops to aero base bars with internal cable routing then you may need new cable housings and threading those housings through many styles of carbon wing style base bars can be a challenge. That is a PITA and tricky no matter who you are. I have seen more than one first timer give up and drag the mess of parts to the LBS to get things properly fished in and out of frames and bars.
The shifter cable housings will likely need to be replaced or at least recut unless by some dumb luck the existing lengths work out correctly for your aero bar extension lengths. Always cut cable housings with a good bike cable cutter like the Park Tools or Pedro variety or something like a Dremel tool with a sharp rotary cutting blade and don't try to do it with general wire cutters. Even with a good tool you'll generally have to clean up the cut ends a bit and open them up so the cable slides freely. One trick is to make the cable cut, do a little clean up with the cutters or a file to remove any crushed bits of the outer spiral cable jacket then insert a cable from the far end of the housing and push it firmly through till it helps open up the cable liner sleeve which tends to get pinched shut when you cut cables and can be hard to reopen from the cut end. While you are right about quality tools - often a high quality cutter costs more than having an LBS do the work to begin with. Dremels are great and all but I prefer a bench grinder with a nice custom jig (that most shops make) that will give you a nice 90 deg end on your brake cables. Not so important to grind your shift cables being as they are radial. Then, if the cables he gets are Nokon, Gore or something fancy - and I hope they are being as they cost the same as OE sets...well, I can not count the sets of cables that are ruined by first timers. Especially Gore.
Other minor gotchas that depend on the style and brand of bar end shifter and brake lever is that many of these require you to get the cables cut to the correct length which means a partial install for sizing purposes, then you have to partially disassemble either the shifters or brakes to securely mount them with the correct sized allen wrench and then reassemble them as you thread the new cable in through the shifting/braking mechanism into the now hidden cable that sits inside the aero bar extension/ base bar and then reassemble everything in place. If your bar extension and or base bar designs do not include completely hidden cable runs then this part is a bit easier. And then be aware of bar twist and on and on and the other "gotchas" many first timers do...super clean install. Super clean shifting....but you can not turn the bars....I always have to laugh.
Bottom line, if you can size and trim brake and shifter cables and housings and deal with things like unwrapping and wrapping bar tape not to mention clamping the various cables and then adjusting the brakes and derailleurs as necessary after completing the swap then the job isn't too hard but it'll likely take you a while on your first try as you figure things out. Just don't do this in a hurry or the day before an important ride or event and give yourself time to work through it and then test ride it to check for any issues. Agreed.
There are a lot of good tutorials out there but the Park Tools website is always a good resource for things like this.
What if the Hokey Pokey is what it is all about?