Hi,
I live in Abbeyfield, Killester which is also zoned a conservation area. I got permission to build an 800sq foot extension no problem. Drive way entrances should be no problem either - it's not as if the houses are protected structures.
If you search, by map, on the Dublin city website in Abbeyfield (since 2005) when it was rezoned a conservation area or since whenever Marino was rezoned, you'll get an idea of what is permissible. In practice most things that would be permissible in a normally zoned residential area are permissible in a conservation area. Good luck.