There are two ways, the first and best is to have the origenal text in Open Office and import from there.
There at different choices, I forget which one it is. When you get to import text, I think the option is to import the writer version of the native format.
The other choice is to put them in Scribus from the text, first highlight the peace you want and change from regular text to Italics or bold but it is tedious to do that.
Hope this helps.
Wena