2 lines in front go to the egr controller. one in back goes to a line under the plastic spark plug cover and another in back goes to another hose dissappearing under the intake manifold (4 lines connected on the car I looked at yesterday).
The other nipple is capped.
If you don't have any lines unplugged, loose (not connected), then there shouldn't be any problems.
You should have a hood mounted sticker that shows the vacuum connections.
If you need more detailed specifics, you could always buy the OEM fuel manual for you car by calling 800-35-volvo (Mottonic 4.3 or 4.4 depending on the year).