jruby -S gem install activerecord-jdbcsqlite3-adapterThis installs the JDBC Sqlite adapter, and should include any dependencies. If it doesn't, you need:
jruby -S gem install jdbc-sqlite3After that, just edit config/database.yml to use the jdbcsqlite3 adapter instead of the normal one:
development:Presto! You're done.
Note that I'm assuming you're using Rails here, if not then you don't need the activerecord gem.