You can override Bootstrap's CSS so that it uses a linear transition instead of an ease-in-out. You can also change its duration from 0.6s to whatever you want. Obviously the more seconds the longer/slower the transitions will be. You will also want to make your interval 1 so that the carousel does not stop on any image.
.carousel-inner > .item {
-webkit-transition: 5s linear left;
-moz-transition: 5s linear left;
-o-transition: 5s linear left;
transition: 5s linear left;
}