You could do it fairly easily, however you may have problems with "words" within words. The example I give below would replace "one" even inside another word (like someone, bone, lonely etc.).
Make an alias that calls a script ...
Alias: *
Label: FixUpWords
Script: FixUpWords
Add this script to your script file (language VBscript) ...
Sub FixUpWords (AliasName, AliasLine, arrWildcard)
dim NewLine
NewLine = arrWildcard (1) ' get line they entered
NewLine = world.Replace (NewLine, "one", "vunn", true)
NewLine = world.Replace (NewLine, "hello", "hallo", true)
'
' add other ones here
'
world.send NewLine
end sub
What this does is get the line you entered, and scan it for each word you want to find, and replace it with the replacement word. You could add extra lines to do more words.
Then finally the resulting string is sent to the world.
You could fix the "one" problem by searching for " one " (with spaces around it) and replacing with " vunn " (with spaces), however then you might run into problems with sentences like this: "I see one, I think" (in that sentence, "one" doesn't have a space on each side).
However with a bit of tweaking you can probably make it work pretty well.