It is possible. I've done it, but I won't help you take the idea and JadedCats hard work for your own pack.
On a side note, it is extremely more grindy if you have a void nether. Have you tried the compressed dirt quest without the ender quarry in the nether?
I don't even know where to begin with replying to this...
I've pointed out several faults with the multiplayer map that gave certain teams on certain islands advantages over others. None of these issues seemed to have caused any concern, so I've done my own hand in making a more balanced multiplayer experience. It's just that, "Hey this one resource is going to be removed because it's too easy for an individual team to monopolize it, so the I would like to also edit the quest that requires that item."
Another thing I wanted to remove, for example, are the magical forest biomes. Some islands have them around and others don't. The ones that have them have a huge advantage at starting Thaumcraft by way of pech trading. The infusion for the greatwood tree sapling is obviously the way its meant to be done. THEN you complete that quest, get a silverwood sapling, and can make your own magical forest.
It's not like JadedCat, or any FTB packs, are released with 100% intention to remain as is and completely uncustomizable. Not every player and server owner likes the default configuration to everything. I'm not even editing the pack per-se. I'm editing the map and a config setting. The pack will still most definitely be Agrarian Skys by JadedCat, a pack which rivals none others in how much I have enjoyed it thus far.
If anything, for a challenging map such as this,
I feel like support to small changes people want to make that make it even more challenging should be welcomed with open arms. I want to make such a modification, but something is failing when I attempt to do so. This is the most suitable and appropriate place I could think of to ask for help.
To answer your question, I have completed the map and have done compressed dirt by way of barrels. I heard about the bore trick, but I didn't like the idea of using it since it's quite obviously an exploit. The dirt left by the ender quarry isn't intended to be mined. In my opinion, honestly, to do that feels in line with
intentionally performing the fluid duplication exploit via fluiducts.
Actually, I just had an idea to throw out, if it's possible: make the ender quarry turn mined blocks into something worthless like green stained clay instead of something valuable like dirt ^_^.
Anyways, I digress. The worst case situation is I don't end up being able to edit that quests but I already have a solution to that. I would just prefer to do it that way.