Some more information about my first problem:
What I want to implement is a finder method that returns X objects starting from the Yth object. Typically used in a web application where we want to display search results (like this forum, for example)
JBossCMP has a declared-sql query specification which is similar to the JAWS finder specification. For more information read the jbosscmp-jdbc dtd, which is documented, or buy the JBossCMP docs.