I must admit that this is the first time I've heard of a library at Iona, missing or otherwise.
Hector Boece @ Boyce @ Boethius doesn't sound like a very reliable source to me:
"Boece wrote and published
Historia Gentis Scotorum (History of the Scottish People). By modern standards it is overly patriotic and has many inaccuracies."
http://en.wikipedia.org/wiki/Hector_Boece
"
The first Viking raid on Scotland occured at Iona, as well as Skye and the other outer isles, in 794 and
the island was attacked several times in the following years. It was during these raids that the chronicle of Iona was lost although a copy of Adomnan's Life of Columba survived on the Continent."
http://www.scotlandspast.org/vikings.cfm
"...many other beautiful examples of what has been called 'the work of angels' were looted and taken home by Vikings..."
http://www.bbc.co.uk/history/lj/conquestlj/loot_03.shtml?site=history_vikings
"...In 794, the Vikings sacked Iona in Scotland carrying off treasures from the Island..."
http://members.aol.com/skyelander/intro15.html
"St Colum Cille's great monastery at Iona was burned in 802."
http://www.wesleyjohnston.com/users/ireland/past/pre_norman_history/vikings.html
Unfortunately I can't nip down to Iona to research it, as I live about 75 miles north of there as the crow flies...
If such a library ever existed, the evidence would seem to suggest that it was either looted and/or burned by Nordic Viking's ancestors!
maximus otter