1. Get Gradle: http://repo.gradle.org/gradle/distributions/gradle-1.0-milestone-1-all.zip
2. Unzip the zip to some directory.
3. Point the GRADLE_HOME env var to /some/directory/gradle-1.0-milestone-1.
4. Download clojuresque: http://clojars.org/repo/clojuresque/clojuresque/1.4.0/clojuresque-1.4.0.jar
5. Put the jar in $GRADLE_HOME/lib/plugins.
6. Tell gradle you want to use clojuresque in the buildscript:

   apply plugin: "clojure"

7. Add clojars to your repositories:

   repositories { clojarsRepo() }

8. Put your clojure sources under src/main/clojure.
9. Run gradle build.
10. Find the jar with your project under build/lib/<project>-<version>.jar.

A minimal buildscript is:

apply plugin: "clojure"

repositories {
    mavenCentral()
    clojarsRepo()
}

dependencies {
    compile 'org.clojure:clojure:1.2.0'
}

Some more information can be found in the wiki.