If you are coming from say South Tipperary, then it's just off the N73 Mitchelstown to Mallow road.
The 5km course is on small roads and trails with the grounds of the park. You should treat this the same as you would an ordinary road race...i.e. wear your normal running shoes. The only thing you may need to watch out for is exposed roots but again, theses are a minor affair. There are a few pulls out along the course but they're small. Expect to set a reasonably fast time.
Please note that the car park within the Park itself closes at 8pm. Make sure you park over near the school. Prizes and refreshments afterwards in the school as well.
As for Doneraile Park itself, it really is a lovely spot. It's basically an old country estate and is now a grassland park with some small forested areas. If you have never been here before then you soon see that Doneraile Park is really an outstanding spot, especially if the sun is shining.
Overall...Doneraile is a stunning spot for a race. If you are taking part in the Cork City Marathon or Half-Marathon next Monday then it would be best to use it as an easy slow run. Great race to kick off the series.