The 'real' way would be to look through the code and modify the values before they are sent to the target fields.
If you don't want to do that (I haven't downloaded the package to judge whether doing that is practical, or even possible), you could try setting the target parameters for the fields you want to edit so they point to hidden elements on your page to which you have attached 'onchange' functions.
Then, every time a value is returned, your function can decide what to do and then copy the truncated/edited text to a visible element.
Note: if this hack works, it has the obvious advantage of leaving the original scripts exactly as they were download. However, it might not work at all, or it might not work for certain fields; in that case it may be necessary to do the 'real' thing (or, if there is a support- or user- group for this widget, inquire there).
Also: even if the feed works as hoped, you will probably still have some one-time work to do fixing display classes which aren't assigned as expected because of the hack.