retrieving keys from a GIN index on a tsvector column in Postgres 9.1?

Hi,
    I've got a collection of documents that I'd like to do some full text searching on in Postgres 9.1, so adding them as the contents of a tsvector and then creating a GIN index on this column seems straightforward enough. My understanding of the GIN index is that the keys used are (depedning on the text search configuration used) either the list of original words or their normalized lexemes from the collection of original documents. However, for other functionality we've developed I'd really like to get that list of keys out of the GIN index to put in another column in a different table for use. Is this possible?

Thanks,
Chris