I'm interested in creating a custom cover page for a DocBook 4.5. Is it possible to tell the toolchain to use a prebuilt PDF page for the cover page? In this case, I would simply create it in Word or Writer, and then add something to the customization layer to use it as the first page of the book.
Its important to have the DocBook toolchain incorporate the prebuilt cover page to keep page numbering and style consistent (i.e., cover-front is 'i', cover-back is 'ii', table of contents is 'iii', etc). So PDFedit and friends are out of the question.
Related (but not required for the question): for those who are interested, I've tried making sense of documents like this. But they ramble on without telling me succinctly what I should do. And adding the following to the customization layer does not change the space before the title, does not change the font size of the title and lacks the logo.
<xsl:attribute-set name="book.titlepage.recto.style">
<xsl:attribute name="space-before">2in</xsl:attribute>
<xsl:attribute name="font-size">32pt</xsl:attribute>
</xsl:attribute-set>
If I change it to book.titlepage.verso.style, then the font size on the second page will change (but not the leading space before the text). Its totally baffling to me, and I'm tired of trying to figure these ill-logical details out.
You can use a pre-created PDF file as a book cover. But in order to merge that cover and the PDF built from DocBook sources, you would need a program such as PDFedit or Adobe Acrobat. There is nothing that you can add to a DocBook-XSL customization layer to accomplish this.
It is possible to incorporate a cover (where a prebuilt PDF might be incuded by reference, as an image) when building the PDF from DocBook sources, but the stock DocBook-XSL stylesheets provide very little support for this.
A cover element was introduced in DocBook 5.0. But in order to do something useful with it, you would have to write the needed XSLT templates from scratch. See the Book covers section in Bob Stayton's book for some more information.
The latter half of the question is about title pages which are different beasts. If you need help with title pages, please ask a separate question (btw, you can also ask at the docbook-apps mailing list; see http://docbook.org/help).