To put a Crown in mono bridge should be explained in the manual. My XLS 402 requires a custom Y cable that inverts the signal to channel 2 from channel 1 so you are actually feeding only the left or right channel from the Pre/Pro to the amp. You then connect both + output terminals to your speakers + and - posts. Some amps might have a mono bridge/stereo switch which would probably invert channel 2 electronically, but I am sort of guessing at that.
Now why are you going to run 3 amps in a tri amp configuration all bridged? Do you only want to listen or have one channel? Also, are you going to be playing this stuff really loud? Pro's use tri amp setups for power puposes. It can give you tremendous output since the lows, mids, and highs are running off of seprate amps. The high are normally horns since a tweeter or even a bank of tweeters would blow trying to keep up with the mids and lows. We some times tried to use Pizoe which are like mini horns, but we always blew them.
What you would need is an active x-over that is feeding to the amps and have drivers without passive x-overs in them. IOW, if you are thinking of using consumer speakers, it isn't going to work. You can use passive x-overs also and forgo the active x-over, but there will be a power loss and that is the whole point of tri amp. You would set the active x-over according to your speaker specs. It is also a good idea to use audio spectrum anylizer when you do this. It has also been mentioned in this forum that stripping out passives and using an active, even if they are set to have identical peaks and slopes can change the quality of the sound.