Vegas has support for the Mackie Control Universal (MCU) and any controller that emulates a MCU should be usable with Vegas.
The US-2400 claims to have three somewhat different MCU emulation modes, intended to be optimised for use with Sonar, Logic, and Digital Performer, and it should be possible to use any of these with Vegas to some extent, though discovering which one will work most satisfactorily with Vegas will probably need a bit of experimentation.
(I use a vastly cheaper controller (BCF2000) which also has a couple of modes that emulate the MCU and I find that it works very nicely with Vegas when used in its MCU-for-Cubase emulation mode.)