I know I've seen this done on a few other maps where Psi Storm and Scarabs can do more damage then normal or be upgraded more. I looked through a few tutorials and found references, but never a step by step on how to do it. Can someone please explain this to me?

Scarab = Go to scarab upgrade and change it from 1 to 255.
Psi Storm = Go to other upgrades and change it to default of 1/1 or so on. (Warning : This will make turrets and scv/other workers have upgrades too)

You need to have starforge or scmdraft. For the psi storm, you can't upgrade the damage in-game, but you can set a upgrade for each player. On starforge, it would be unused upgrade 60. On scmdraft, it would be the last unused upgrade.

Just some clarification, does it need to be 255 or can it be any number in between?

Any number in between - the scarab's damage will be x + uy, where x is its base damage and y is its upgrade damage and u is the number of upgrades. You can set it to any number of upgrades, but in the game you can only upgrade it once (using the Scarab Damage research).

If you set the upgrade max for scarab damage higher, you can upgrade more than once in the game.

True. The reason an upgrade exists though is because of the once-only normal melee upgrade.

There are eleven Unlabeled / Unused Other techs in SCMDraft, are there any tutorials or references on what those are about?

If you can't find it in SCMDraft, just preset it for all of it. It doesn't have any other effects.

The unused upgrades were upgrades which were removed from SC: BETA, some of which include After Burners and Roar, Unused Upgrade 60 is the only thing you really need to know though.

Scarab damage upgrade is like any other weapon upgrade (e.g. terran infantry) you can upgrade as many times as you want (max. 255) and each time the damage is increased.
Other upgrades (non-weapon upgrades in general), like khaydarin amulet (increased mana for templars), can also be upgrades 255 times too, but only the first upgrade adds energy. All other upgrade levels won't do anything but they cost ore/gas.

Which one is that in SCMDraft?

It has already been said:

Ah, I missed that, thanks.

As a side note, none of the upgrades do anything apparently. Only upgrade 60.

Reaver upgrades are shared with other players while giving them to them (your upg can never decrease, only increase).

They do? I thought only tech could be increased through giving.

whats upgrade 60 do??

Upgrade 60 does a lot of things. Most notably, it increases psi storm's damage. 1 upgrade of upgrade 60 increases psi storm's damage by 32, I think. If anybody knows for sure, please confirm. It also increases the damage for units that do not normally have upgrades for their damage. Examples would be an scv, sunken colonies, missile turrets, spore colony, drone, photon cannon. It also upgrades armor for units that do not normally have armor upgrades, such as buildings and critters.

A psi storm hits 8 times. Each time it does 14 damage, adding up to a total damage to 112.
For each upgrade of upgrade 60 each hit of the storm will be increased by 1 damage, thus effectively adding 8 damage to the storm. So if you set upgrade 60 to 30 the storm will do 112 + 30 x 8 = 352 damage.