I left Bellevue a long time ago, so I use OpenOffice.org for my word processing needs. OOo allows search and replace based on regular expressions or format tags.
I recently discovered the OOo extension <a href="http://lukesblog.it/ebooks/ebook-tools/writer2epub/">Writer2epub</a>.
Writer2epub will generate a valid epub from a document, separating it into chapters based on heading tags if you wish (or not, if you don't).
One long-out-of-print book I wanted was available to me only as a single big blob of text. I used OOo and Writer2epub to make a nice book out of it.