There is no way in mirc to simulate a new line in the way you want it too. Other than playing to the channel line by line, you could play to an alias which appends each line to the previous line (using a var) then msg that to the channel. Sample output:
<ConfuzzedBot> Current Work Unit ------------------ Name: p753_vln2.8nopbc Download time: September 16 15:22:37 Progress: 6% [__________]
You could also manipulate the format of the display this way, by having it find just the info you want from each line and ignoring the --- line etc. But then you might as well just use $read or fopen instead of play.