I have not used the plug-in for WordPress, but I use plogger a lot. Below is an "overview" of installing plogger on Dreamhost, much of which is probably relevant for your case:
I suggest you look at the documentation for the plug-in, and see if it uses the existing WordPress database, or needs its own. If it needs it's own, the above instructions should work. If it uses the existing WordPress database, then just visit the Control Panel-->Manage MySQL page indicated above, and copy the relevant information from that screen for the database in use by WordPress to complete the necessary database info for the plugin. Good Luck!