As Alan Hay mentioned you could externalize the datasource configuration into Tomcat's own context.xml and then have Spring do a JNDI lookup to retrieve it. This is an approach that I've commonly used on some of the projects I've worked on.
The pieces you need to put in place to achieve would be:
1. Add the datasource configuration to $CATALINA_HOME/conf/context.xml
<GlobalNamingResources>
<Resource type="javax.sql.DataSource"
name="dsName"
factory="com.jolbox.bonecp.BoneCPDataSource"
driverClassName="your.driver.classname"
jdbcUrl="your:driver:url"
username="username"
password="password"
idleMaxAge="240"
idleConnectionTestPeriod="60"
partitionCount="3"
acquireIncrement="10"
maxConnectionsPerPartition="2"
minConnectionsPerPartition="2"
statementsCacheSize="50"
releaseHelperThreads="3" />
</GlobalNamingResources>
2. Add a resource link in the application's META-INF/context.xml
<Context path="/YourApp">
<ResourceLink description="Datasource for YourApp"
global="jdbc/dsName"
name="jdbc/dsName"
type="javax.sql.DataSource" />
</Context>
3. Modify the Spring config to lookup the datasource in JNDI
<beans xmlns:jee="http://www.springframework.org/schema/jee"
xsi:schemaLocation="http://www.springframework.org/schema/jee classpath:/org/springframework/ejb/config/spring-jee-3.0.xsd">
<jee:jndi-lookup id="dataSource"
jndi-name="java:comp/env/jdbc/dsName" />
4. Move the driver and datasource jars
Since the datasource configuration is now container managed, you should place the database driver and datasource jars into $CATALINA_HOME/lib so they are available to Tomcat when it creates the datasource. These jars should no longer need to reside in the WEB-INF/lib of your application.