It's going to be much harder since you don't have a monitor - can you borrow one for an hour or so? If so, you can install VNC on the Quicksilver and Chicken of the VNC on the PB (both free, both easily found on the web), then remotely control the Quicksilver via the PB.
You could also spend a fortune on Apple Remote Desktop, but it isn't necessary.
While this is all somewhat indirect - you're going to be using a remote connection, not wiring the monitor, KB, and mouse to the Quicksilver - there are some plusses:
(1) You can use the PB and switch over to remotely controlling the other Mac as you see fit - no plugging and unplugging cables.
(2) You can connect wirelessly, should your equipment be properly set up.