Random Letter Cycling Actionscript

Hi.

I am trying to make a random text generator for my hover links in actionscript, so that when you hover over it generates a random text effect before settling on the chosen word, which is all contained inside a movie clip.
I would like the random text to start of with .... .... ....'s, one dot for each letter and spaxces for spaces. The for the random letters to start from the left, for example:
tx.. .... ....
gbzw .... ....
jfjk lo.. ....
etc until all the dots are replaced by randomising letters. I would like it to keep randomising for a couple of frames, then start forming the words in the same way, from the left, for example (CAPS representing the real letters, not actually in caps):
THjl mhgf llop
THIS lljj popf
THIS LIgf yu
etc until the word is formed.
I would quite like this effect to take place over about 2 seconds, with the word and time as variables so I can use the same movieclip for each link, just changin 2 things. If anyone could do this for me, I would be grateful.

Thanks.. Ash.