Well, if all you have left at this point is a trash can full of live rock, then life will get a lot easier....sadly. I don't mean that sarcastically, but fixing your live rock situation is pretty simple.
You should procede with the live rock as if it is band new, non-cured live rock. Curing live rock requires either a lot of equipment and water changing, or a lot of patience. Either way you will end up with decent live rock.
However....I would strongly suggest to you that something is very wrong if you simply moved live rock from a tank that had been set up for a long time to a trash can that has adequate water quality initially, and lots of water movement, and you have nitrate and nitrite and ammonia spikes. REALLY cured live rock should be able to be taken from a tank and placed into good water with adequate movement with almost no trace of nitrate, ammonia or nitrite. A very small spike might occur, but nothing that should be detrimental if the water circulation is adequate and the water you start with is decent. 'Spikes' will mean you did something wrong. Period. Either the rock was out of the water too long, had a coral or other animals which were not removed and are rapidly decaying, or that your 'new' water had some toxin in it.
Other possiblities include putting the live sand from a tank into the same trash container (by the way....this is assuming that you used a trash container that has never...ever....ever....ever had anything in it and was cleaned before you used it so that there are no potential contaiminants) as the live rock. If you happened to have moved the live sand from the bottom of your friend's tank, you WILL likely see a spike in Nitrate, Nitrite and Ammonia. Additionally, and actually MORE TOXIC, will be a spike in sulfa-dioxide (rotten egg smell!!!!) which is extremely toxic to fish and any inverts which process oxygen. This is because when you move large amounts of established live sand from a tank that is 'long' into a container that is instead 'deep,' you end up with a massive (within 24 hours or less) die off of anaerobic and aerobic bacteria which was growing in striated layers in the sand. When you move the sand from a long tank to a deeper situation, the anaerobic bacteria comes into contact with too much O2 and can die off. Alternately, the aerobic bacteria is trapped deep in the sand and dies off almost immediately....subsequently relasing a few hours later massive quantities of sulfa-dioxide which produced that rotten egg or rotting smell. When this occurs you might see a lot of bubbles being released into the tank from the sand or live rock. This is BAD!!! Anything which 'breathes' will die quickly when this occurs! Fish will get red streaks through thier tails similar to hemorrhegic sceptocemia (sp?) as their blood gasses become toxic. They breate harder, introcucing more and more toxic gas into their bloodstreams resulting in death....sigh.
So......long way to say that you might have 'gassed' your fish by subjecting them to sulfa-dioxide inadvertently. This is most assuredly what is occurring with your live rock.
For your live rock....HUGE water change, followed by VERY aggressive water movement and aeration. If there is live sand in that trash container, REMOVE IT and get it into another container with simple power head movement. It will gas itself off in about 3 days and be fine...but be aware that this will happen again if you go from a shallow layer to a deep layer in the tank you transfer that sand into.
Whatever you do, do NOT add chemicals that stop or inhibit the nitrogen cycle to your live rock you are trying to tend to....for example....don't use Amquel becuase, while it might stop ammonia from being absorbed by your fish's gills, it does this by stopping the nitrate cycle and does not allow the ammonia to complete it's natural conversion from ammonia to nitrite, to nitrate. Additionally, these types of products may produce false-positive readings on many water tests, leading you to believe that your water is now safe. So stay away from those and let nature take care of this with good water, water movement, aeration and light.
Sorry you lost your fish! Hope things improve for you....be PATIENT!
God bless.....