I know this has come up in discussion before and I realize there are multiple solutions to this. This seems to be the easiest fix I've found for fadas on a PC computer.
<DISCLAIMER>: I don't know if this works the same way for all computers worldwide. I live in the U.S. and verified these methods on U.S. computers using U.S. versions of the operating system.
I came across a link yesterday when I hit my rope's end while trying to type fadas using alt and the number pad i.e.
alt+130=é
alt+160=á
alt+161=í
alt+162=ó
alt+163=ú
alt+144=É
alt+0201=É
alt+0193=Á
alt+0205=Í
alt+0211=Ó
alt+0218=Ú
I know. Talk about a pain in the thóin. Anyway, yesterday I cam across this link:
http://support.microsoft.com/kb/306560
It gives the step by step directions for windows users to change their keyboard setting to an international keyboard. What this does is allow you to type fada letters with just 2 keystrokes (3 if capital). For example now when I want to type á, I just type an apostrophe followed by the letter. If I need Á, I'll type the apostrophe followed by shift+a. Nice and easy.
There are different methods if you're a mac user (I go back and forth bewteen the two systems). The mac methods can be seen here:
http://talkirish.com/forums/t/26.aspx
On another side note: I have found that if you are an iPhone user, if you go to your settings, general, international, and change your region format to Ireland (Irish), not only does it change you calendar to Irish but as you text in Irish your phone will be begin to recognize and eventually auto-correct Irish. I haven't researched this in depth but I recently notice that while I was texting I typed "slan" and my phone corrected the word to "slán" when I hit the space button afterwards. Granted, this didn't happen for probably the first 5 times I typed the word after switching my region format to Irish, but it does now. Another thing to keep in mind (at least my iPhone 4S does this) is that once your phone starts auto-correcting properly in Irish, the words will still have that red dotted underline singnaling a misspelling, so you have be attentive to what your typing. If anyone has any questions regarding Irish on the iPhone I'll be happy to answer them to the best of my knowlege. I'm a bit of a tech geek and I tend to discover things like this by accident.
Hope this helps.