Maybe. It will function, but control depends on your motherboard, and they basically never document it. If you have a fan that can be used, try it. The worst case will be that it runs at 12V always, so cooling will not be compromised. If you're already using the other two channels, just swap one of them, and see if you still get speed control.
As an example, I have an older Gigabyte, and 3-pin are not controllable via BIOS settings, but software control for them works fine. Most fans don't use that much power, so unless running a high-RPM fan, you can typically split motherboard headers just fine, too, if the 4-pin is not controllable as a 3-pin (IE, two fans on one header).