a) You can use low-level ElementBuilder and ElementWriter to place text on a PDF page as shown in http://www.pdftron.com/pdfnet/samplecode/data/Text2PDF.zip
b) If you are developing under .NET you could place the text from TXT to a FlowDocument which you can convert to PDF and Silverlight XOD as shown in Xaml2Pdf sample (http://www.pdftron.com/pdfnet/
samplecode.html#Xaml2Pdf)
c) Finally, you can warp the text into HTML body and convert the resulting string to PDF / Silverlight as shown in Html2Pdf sample http://www.pdftron.com/pdfnet/samplecode.html#Html2Pdf.