I actually have friend summon capsules, but I'd need to head to TNN first. If you're an elf or elf-allied though, I won't be able to summon you. (I'm giant-allied.) Add me in game when you see this and still want to go to TNN through me.
If you do not find someone in a timely fashion in the future:
You should still have the "How to Reach Tir Na Nog" keyword if you have gotten up to/past the G1 quest. You could still talk to Kristell for the Black Pass to reach TNN manually.
Alternatively, if you're looking to train windmill on zombies, you should just do "Their Method." That way, you can choose the mode of difficulty you need for the specific requirements. Besides, they spawn in groups of four. It'll be easier to pile them together (provided you can't one-shot them with windmill and need to change the finish rule of the party you're in), and windmill all four at once for the "Attack / Defeat several strong monsters" requirements. ^^
Quote from Xazreal;1228817:
It can't warp the whole party like the Goddess Wings?
Nope, warp imps only transport their owner.