How do I display lines from a text file as the source for a listbox wizard dialog?

I have a loop that reads the text file line-by-line, but I cannot find a way to concatenate the lines into something that works for the "List Box Text". All I get is a single item in the list. I have tried using the following when joining the lines back into a single string:
\n
|
<7ch>
\r
<13,10>


Rather than having to build a string, is there a way that I can just specify that the "List Box Text" should come from a data file?