The Wicklow Trail 44k or 22km is not like any road race! For a start it isn't as hard on the joints. Second, a lot of people walk the uphills. The ability to navigate is also a (small) factor. It's quite a different experience, but you would still need to be able to keep going for at least three hours if you want to survive the longer distance. I would suggest regular two hour runs in the hills until about two months before and then up the time to three hours for a few weeks, leaving room for a two week taper.
A bit of background: the race was founded by Maurice Mullins about ten years ago and taken over by the off-road/orienteering enthusiasts in Crusaders AC two years ago. It is a not-for-profit race - in other words, any surplus after we've paid for the hand-made Geoffrey Healy pottery mugs goes to a designated charity (we gave Eu300 to Stride Ethiopia, a charity which supports an athletic club in Yirgalem, Ethiopia this year). We try and keep the entry fee as low as possible - the mugs are about Eu12 each so that's our main expense.
Next year's race is pencilled in for Sat April 5th; check www.imra.ie for updates.