Can you emulate a sever on your own PC to practice?
 

Like, suppose I wanted to try running across SG a bunch of times to see if I can do so without agro. Is there a way to have my own test server to do this?

Yes > http://www.eqemulator.org/

Should only take a few minutes to set up a stock vanilla server. However keep in mind it's going to be OoW era I believe, or wherever PEQ currently stands. So any changes to make SG exactly like it is on p99 you'd have to manually do yourself.

I'm pretty sure they never changed the SG zone files on live, which means the run itself (if that's all you want to practice) should be the same regardless. What will be different (potentially) is where all of the mobs along the way are, but you don't really need them to be there (and be accurate) to learn the run itself.

aftermath already has a server like this where they practice locking down mobs from the rest of the server. Isnt this place great?

As Loramin says, mob placement and pathing will vary a lot on P99 to the standard PEQ (and it's a big, time-consuming part of zone content development here) - probably not worthwhile.

The sg run is super easy to learn here. Never be afraid of trying new shit, the danger of death is what makes it fun, especially when you master whatever new trick youre trying. Currently, im dying in kael on my druid trying to figure out how to split a wolf to pet solo

from CS : jump into the water, go left, then always straight and go to the top to leave water. Once u leave the water take the 2nd tunnel to the left and then always straight and u will zone to WW !
I don't even need Divine Aura to do this on my 56 paladin anymore, that's easy once u know the way.
Like Metham said : just try it, u'll probably die like I did the 1st time, but then u'll be safe

Edit : I believe it's impossible to do it without aggroing fishes in the water, but if you'r a tank class, u'll still be able to do it

Yes you can. I did it myself using Virtualbox and Linux. There used to be a server setup on EQEmu named Morrel Thule that gave you GM access. You didn't have ALL commands but you had most of them. I used it to learn the VP zone.
None of the mobs were the same but the zone was the same so learning the tricks of the zone was handy.

That server eventually died so I setup my own as mentioned above for private use.
The server will be registered with EQEmu and even show up on the server list (when it's running). So you can login with your normal P99 account and click on your server there. But unless you setup stuff in your firewall and such only you will be able to connect.

About 25% of the time i do it on my warrior i make through without the seahorses aggroing and breaking my invis, haven't figured whats different when this happens but it does happen

Mobs can only agro on a tick. I have made the run through SG on a naked mage.