Hi Matt,
We'll hopefully have a new release of Substeps out soon, however in the meantime you can override the version of selenium that webdriver-substeps pulls in. In your pom.xml file you will have a dependency on webdriver-substeps similar to the fragment below, if you add the highlighted sections you can use a different version of selenium-java.
<dependency>
<groupId>com.technophobia.substeps</groupId>
<artifactId>webdriver-substeps</artifactId>
<version>${substeps.webdriver.version}</version>
<scope>test</scope>
<exclusions>
<exclusion>
<groupId>org.seleniumhq.selenium</groupId>
<artifactId>selenium-java</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>org.seleniumhq.selenium</groupId>
<artifactId>selenium-java</artifactId>
<version>2.35.0</version>
</dependency>
I hope that helps
cheers
Ian