Apart from playing the odd IMX tape in our J30s don't think I can help much. I'd image with the right driver in a PC Vegas could work with it but I've not heard of such a thing. Does Sony have a driver for the other end of the IP connection?
Also IMX is only mpeg-2, once you got the footage captured as a file on a PC it's more than likely Vgeas could opne it. Interesting idea as feeding IMX down SDI must be fairly lossy. Finding an easy way to edit IMX would be good, it has had a bad rap in that deprtment in the past.
My colleagues reported they tried the process using XDCAM Export option in Vegas. But it seems like this way it does not work. They did not find a way to directly communicate between Vegas and an eVTR.
What seems to work is using a certain network utility outside Vegas to import/export an eVTR stream/IMX file.