I was camped at the Irenabyss a year ago today! A very special place, there's no doubt about it. You can see a few notes
here and pictures
here.
But I deliberately did not include detail of the route and campsites as it is a sensitive area, and a VERY difficult walk in some spots, and you really need to know what you're doing.
Note that there are a few slight variations on the route between the Irenabyss and Victoria Pass. My preferred route varies to the one described by John Chapman in order to completey avoid the bog and leeches of Mary Creek Plains, and requires somewhat less scrub bashing (from what I understand from talking to people who've walked the Mary Creek Plains route. If you look at the various Tasmap publications you can actually see John Chapman's described route on one of the maps, and my preferred route on the other. I can PM some very detailed information if you like.
However, even on my preferred route, there were several bands of very difficult scrub bashing and Bubs Hill should not be underestimated. It looks rather thick from the road, but until you actually start on the hill itself, you have no idea!
It's not just the thickness of the scrub, but how steep it is and that you can't actually see where you putting your feet, and quite often it is on loose scree amongst thick scrub (how is that possible?). There was also no good campsite for our last night (but we managed to find a tiny patch of grass just the right size for out tent), and no creeks or lakes between the Irenabyss and the top of Flat Bluff (if you skip Mary Creek Plains). We drank only from yabbie holes and puddles for a fully day and a half, including our last night's camping and cooking.