Get in contact with the NPWS, they are extremely helpful and will help you organise your visitors hunting permit.
You will need written confirmation from from the landowner that you have permission to hunt deer, a copy of your visitors liscence and they will issue a stalking permit.
National Parks and Wildlife Service,
Main Street,
Ballybay,
Co. Monaghan
Telephone 042-9748754
00 353 42 9748754 from the UK.
Ps, it's probably easier to travel across by boat rather than fly.