At the top of the file PermAlmalexia.lua you find this table

mementos = {
		-- https://esoitem.uesp.net/viewlog.php?record=collectibles
		[336]  = { abilityId = 21226, name = GetCollectibleName(336), delay = 500, cooldown = 3200 }, -- Finvir
...

Check the link provided there https://esoitem.uesp.net/viewlog.php?record=collectibles for collectibleID and the abilityId you want to add,
add a new line to the table, just above the closing } of the table (last line currnetly is
[10652] = {abilityId = false, name = GetCollectibleName(10652), delay=500, cooldown=200}, -- Soul crystals of the returned )
like this:

[newCollectibleIdHere]  = { abilityId = abilityIdOfCollectibleHere, name = GetCollectibleName(newCollectibleIdHere), delay = 500, cooldown = 3200 }, -- Name of collectible here

Campfire kit should be collectibleId 8008:
https://esoitem.uesp.net/viewlog.php?action=view&record=collectibles&id=8008

Not suree where you get that abilityId from though...
The last lines got abilityId = false so maybe try this entry:

[8008]  = { abilityId = false, name = GetCollectibleName(8008), delay = 500, cooldown = 3200 }, -- Campfire kit

Change thje delay and cooldown (both are in milliseconds) according to your preference.

Make a screenshot ingame in ESO and watch the path shown top right -> Note it down.
Should be e.g. c:\users\your windows username\documents\elder scrolls online\live\screenshots

Now strip the \screenshot at the end and instead use \AddOns.
Go to the subfolder PermAlmalexia and edit the file \PermAlmalexia\PermAlmalexia.lua with a text editor.

Search for:
mementos = {
[336] = { ... },
[...] = {....},
} <<<<<- Closeing table mementos

This is a table and it closes the table with the } bracket, after all the lines with [number] = { data here }
-> each line with [number] = { data here } is 1 memento already added currently.

So after the last line with the current mementos (oreven at the top before the [336] ... line, you simply add a new line:
[8008] = { abilityId = false, name = GetCollectibleName(8008), delay = 500, cooldown = 3200 }, -- Campfire kit

Then save it and /reloadui ingame if you were logged in to reload the user interface and make the changes load.
Then check if you can select it from the settings now and if it works.

You can change the values of delay = 500, cooldown = 3200 to other values, where 500 and 3200 are milliseconds so 500 is half a second and 3200 is 3,2 seconds.

delay = waits before it starts I guess?
Cooldown = time after which the memento can be used again