Hi evilphish,
If you want a direct line to one extension, use line assign (#206 option 3) to assign the lines to the vm. In the voicemail, assign line ownership and specify the extension for each of those lines. The attendant will not answer those lines, but rather the personal greeting for the extension will be heard. Only assign the line to the extension using proceedure (#301) unless you want the line to appear on other extensions. You can either delay the ring or have the line not ring. The vm coverage can be delayed if you have an ACS. R3 or later can delay for individual extensions (#321). Make sure you extend the transfer return rings to one more than you max. vm cover rings.
-Chris