I wish someone had posted a solution sooner, particularly those who responded in other threads with simply, "ok, got it working"
<solution>
I added SQLLIB\Java\db2java.zip to JavaUserClasses= in notes.ini, and got a different error message, which copying db2jdbc.dll from SQLLIB\bin to Notes resolved. It probably would have worked if I put SQLIB\bin in the Path env var as well.
</solution>
See further discussion at
http://www.laneyconsulting.com/web/blog.nsf/plinks/NLAY-5VKHTC