Bedsides Simon's good suggestion of writing a custom function, you might consider whether the expected rows would fit in cache, and, if so, a series of separate UPDATE's enclosed in a transaction might be sufficiently speedy.
-- or, a CTE can be used with a table of search/replace strings.
-- or would just formatting a big UPDATE not meet your need? I imagine a dozen replacements as something like:
<code>
UPDATE myTable SET data =
REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(
REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(
data,
CHAR(13), '~' )
,CHAR(10), '~' )
,'division', 'unity' )
,'fear', 'serenity' )
,'greed', 'charity' )
,'travesties', 'justice' )
,'suspicion', 'empathy' )
,'depression', 'joy' )
,'hate', 'love' )
,'poverty', 'sharing' )
,'xenophobia', 'friendship')
,'copyright', 'blessing' )
;
</code>
Donald