http://www.groireland.ie/getting_married.htm
There's the link with all the info. Have a good read through it.
A couple of things to bear in mind though.
In Ireland the couple must give 90 days notice to the Registrar in the area they wish to marry. This may be done by postal notification in certain circumstances but prior arrangements with the Registrar must be made.
The marriage cannot take place until at least 90 days have passed after sending the notice of intent to marry. For example, you serve notice to intent in the beginning of January; the earliest you could marry would be the beginning of April. However, it is also dependant on dates available where you want to marry, whether it be in the Registry office or a church. Many places (Dublin in particular) you could expect a wait of 6 months or more just to marry in the Registry office simply because there are no open dates. Also, if you are able to send the notice of intent to marry by post, you'll probably have to wait till less than 3 months before the wedding to actually enter Ireland; the visa-waiver is only valid for 3 months, and they don't have anything like fiance visas.
So, I guess it depends on what your's and your partner's plans are. If you want to marry in Ireland and don't mind the waiting, then it's definitely do-able. If you are wanting to get married in the near future and move here, then marrying in the US would be your best bet.