UO Fiddler or mulpatcher programs can be used to import animation in .vd format. I prefer to use a mulpatcher for working with animations, it is clear and simple for me. It also allows you to extract the animation as individual frames.
Be careful when doing this, because I added so many new animations that UO wouldn't load anymore. I had to find a program that patched client.exe to run higher than 2GB of memory. I can't remember where that was I found that patcher, but just keep an eye out that if your client stops running...this may be the reason why.