I just went through setting mine up the other week. Be damn carefull when setting it up and do not run the die too close to the blade! Or you will take a nice thin layer out of your die top ... Ask me how I know ;-)
In my 650XL, I had to run the die down very deep and it leaves barely any room to see inside the window, so you really have to watch it carefully.
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Install the die without the trimmer in the position you want. Typically station 4 in a 650XL. Don't forget that The trimmer takes up 3 entire stations once the vacuum attachment is installed.
What I did was take a case already trimmed to the proper length wanted (checked with a caliper) and then remove the shell plate locating pin and place under the die.
Raise the shell plate to the top and run the die down until the mouth of the case is just barely visible above the die, about a mm or two. Tighten the die with the case in it.
Then install the trimmer and run down till the blade touches/rests on the case mouth and tighten.
Lower the shell plate and use a light to be very sure that the blade does not touch the die surface or that blade could shatter.
Put on a pair of safety glasses, hold the trimmer very tight with one hand and turn it on to ensure it spins freely (be ready to turn it off if it hits!!!). It has a ton of torque so always hold it firmly before turning on from now on.
If you have other dies installed (RCBS Lube Die, sizing die, etc), make sure there is a shell case in every die before fine tuning (the 650XL tool head flexes and you need to set the height with a stable shell plate and tool head.
Run a few over sized cases into the trimmer without the vacuum attachment and then measure the size after trimming. Adjust the trimmer slightly up or down to get the size you want and make the final tightening with a case in the die (in all dies actually).
Then install the vacuum attachment and enjoy!
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I have my .223 prep tool head setup with an RCBS Lube Die #1 in station one, Dillon .223 full length sizing die with the decapping pin broken off in station two and the trim die in station four. Stations three and five are empty (good to use for checking the case mouth for damage etc while running them through) and they are unusable due to the vacuum fitting.
Note that you can't simply remove the decapping pin from the Dillon die as the carbide ball neck expander is attached to the thread that the pin is on. Your get oversized cases if you don't use that ball. Simply break off the thin bottom portion of the pin (you normally get a spare in a Dillon set anyways).
This setup is awesome, all I do now is dump a ton of cases into the feeder, no mess or fuss and no lubing cases by hand or baggies etc, grab a beer and pull the handle.
Then on your main reloading tool head, install a decapping die into station one as a safety measure (I used a lee rifle decapping die since it had one on hand).
Cheers
Tim