The PWM fans use a 4 wire connrection (12VDC, Ground, Sense and Control)- the fan controller doesn't need the control since the fan controller is using a rheostat to control fan RPM rather than the fan reacting and modulating current.
So it depends on what connections to the fan controller are required -if it's a 4pin (fan) to 3pin controller then
one of these is basically what you want. A fairly quick and easy method - although it does add extra cabling. An alternative is to buy a few
3-pin plug connectors, disconnect the four fan wires from their plugs by gently depressing the metal tabs that hold the connectors (they snag into the four thin slots in the plug end- easily seen in the eBay link -tho' there are only three there of course for a 3 pin), slide the connectors out, raise the metal tab on each connector again- it will be lying flat after you depressed it to release the connector, and slide the connectors into the 3-pin block.
These pinout diagrams will help. The pin/cable you don't need is the Control (usually blue)- you can either snip off the connector on the end or tape it out of the way and insulated from any circuit. A quick look at the
NZXT Sentry shows a 3-pin connection is used.
Bear in mind that controlling fans via a rheostat/contoller means not setting the fan speed to low- at least at fan start. Too low a speed means a low voltage, and it may not be sufficient to start the fan in motion - this will cause fan motor damage.