Yes there are various ways of modding Fallout on the 360 with varying capabilities. The most capable is using a JTAG'ed 360 or a developer's kit. With these you can apply G.E.C.K. mods, normally only available on the PC, onto your console. Developers Kits are very expensive and rare so these usually aren't an option for most people. To apply a JTAG to your console your console must meet certain specifications and requires you to modify your console. Doing so is a complicated process and if you don't know what you are doing then it could cause irreversible damage to your 360 whilst also voiding the warranty.