This is not a step-by-step, just a brief overview aimed at pretty competent mechanics ; I could have done with this info to speed up changing mine.
Honda wanted 1.100€ here, parts and labour ; the same Denso DAN985 is available on the net for 246€, it took me 4 hours including making the belt-tensioner tool, and next time would be less than half that.
There's a series of pictures on the French Cardisiac forum, here, with a French text that is pretty inaccurate.
https://forum-auto.caradisiac.com/topic/93607-tuto-révision-complète-honda-frv/page/2/
Look around 18th October 2018.
It also shows the revised belt-layout which all cars have probably had done, by now, but if you've got the superfluous jockey pulley and longer belt still, ditch the pulley and change the belt for the shorter type.
Basically you need to get the header-tank and power-steering reservoir loose, and pull them to your right to get access to the belt.
Removing the belt tension requires a 14mm socket welding to a bit of 30 to 50cm flat strip, something like 30mm x 4mm is good, the socket will need the square cutting off so you've just got the 6 or 12-points, thinking about it 12 is a lot better as you haven't got an awful lot of movement available and the inclination is important.
Your tool is pulled forward, the belt slackens, and you can slip it off.
Photograph the bonnet lock position, pay attention to the adjustment marks, run a pen around the plate, it will avoid having to readjust everything afterwards ; then remove the 2 x M6 from the front and the 1 x M6 from the back.
Then get off the plastic shroud over the front traverse, followed by the top radiator support brackets, and the front traverse unbolted and pulled font-left (it won't come off completely as there's the bonnet-cable and harness fastened underneath).
Remove the top radiator-to-header-tank hose at the radiator, block the rad stub with a blind bit of pipe, and kink/strap the hose to keep all liquids in.
The RHS (in car) cooling fan block has to be removed ; it's held in by 2 bolts top, 2 bolts bottom, one pipe-retention bolt on far RHS, all 10mm socket on small 1/4 ratchet. Find all the electrical sockets-plugs on that fan block, there are 4 maybe 5, unplug them all, WD40 everywhere helps dismantling.
It's a bitch to get out, get lots of light down there to see what's snagging, and mind you don't break the rad header stub at the top.
Once dragged up and right, the alternator comes off with 4 x 12mm headed bolts, watch the lengths, the 3 long ones are of 2 different lengths.
REMOVING IT IS TIGHT and best protect the rad fins with a bit of thin alloy/zinc/steel sheet as you will scrape these badly trying to fight the alternator up past the air-con hose, the sheet will help it slide.
Re-fitting is simple reverse of the above ; grease all your M6 bolts going back together, much easier to reassemble.
You'll probably break almost all of the pip-clips both on the top plastic cover and the lip under the rad where you'll need to pop some out to get access to the bottom ; it's a good idea to buy 20 of these off Ebay as they're needed everywhere on these cars.
Apologies if I've forgotten anything, it'll be minor and self-evident.
