Announced earlier in the week, Bethesda sent out a tweet regarding an stream that would show off modding support for Fallout 4 for Xbox One. This stream occurred on May 27th, 1 p.m. and can be viewed on the archive here or in the YouTube video below. Modding support was released from the go for PC due to the versatility. Modding on a console is more of a big deal due to the inability to provide mods for previous Bethesda games on consoles.
Before the stream, Bethesda had sent out invites to select few Fallout 4 on Xbox One owners to beta test the mods before its grand reveal. There are obviously some limitations mentioned including the mod being only 2gb in size at most and that the PlayStation 4 version will be getting the modding integration the month after the Xbox One mod integration release.
The modding support for Xbox One will be available on the 31st of May. As time goes, there will be a few mod authors from the PC version who will approach the change and port their work over. In the meanwhile, fans will just have to play the waiting game.