Use the HTML classes in animate.css as LESS mixins.

animate.less

/*
Animate.css - http://daneden.me/animate
LICENSED UNDER THE  MIT LICENSE (MIT)

Copyright (c) 2012 Dan Eden
*/

.animated {
  -webkit-animation-fill-mode: both;
	-moz-animation-fill-mode: both;
	-ms-animation-fill-mode: both;
	-o-animation-fill-mode: both;
	animation-fill-mode: both;
	-webkit-animation-duration: 1s;
	-moz-animation-duration: 1s;
	-ms-animation-duration: 1s;
	-o-animation-duration: 1s;
	animation-duration: 1s;
}

.animated.hinge {
	-webkit-animation-duration: 2s;
	-moz-animation-duration: 2s;
	-ms-animation-duration: 2s;
	-o-animation-duration: 2s;
	animation-duration: 2s;
}

@-webkit-keyframes bounce {
  0%, 20%, 50%, 80%, 100% {-webkit-transform: translateY(0);}
	40% {-webkit-transform: translateY(-30px);}
	60% {-webkit-transform: translateY(-15px);}
}

@-moz-keyframes bounce {
	0%, 20%, 50%, 80%, 100% {-moz-transform: translateY(0);}
	40% {-moz-transform: translateY(-30px);}
	60% {-moz-transform: translateY(-15px);}
}

@-o-keyframes bounce {
	0%, 20%, 50%, 80%, 100% {-o-transform: translateY(0);}
	40% {-o-transform: translateY(-30px);}
	60% {-o-transform: translateY(-15px);}
}
@keyframes bounce {
	0%, 20%, 50%, 80%, 100% {transform: translateY(0);}
	40% {transform: translateY(-30px);}
	60% {transform: translateY(-15px);}
}

.bounce {
	-webkit-animation-name: bounce;
	-moz-animation-name: bounce;
	-o-animation-name: bounce;
	animation-name: bounce;
}

layout.less

@import "animate.less"

/* Let's say you have a navigation with some <span class="icon"> elements that you want to animate on :hover */
.selector {
    a:hover {
        .icon {.animated(); .bounce();}
    }
}