Use
@org.jboss.ejb3.annotation.Pool(value="myPoolName")
annotation on the EJB referencing your custom pool as defined in the standalone.xml :
<pools>
<bean-instance-pools>
<strict-max-pool name="slsb-strict-max-pool"
max-pool-size="20" instance-acquisition-timeout="5"
instance-acquisition-timeout-unit="MINUTES" />
<strict-max-pool name="mdb-strict-max-pool"
max-pool-size="80" instance-acquisition-timeout="1"
instance-acquisition-timeout-unit="MINUTES" />
<strict-max-pool name="myPoolName"
max-pool-size="20" instance-acquisition-timeout="5"
instance-acquisition-timeout-unit="SECONDS" />
</bean-instance-pools>
</pools>
[edit] without the annotation :
Using the pool namespace (urn:ejb-pool:1.0) in jboss-ejb3.xml (jboss specific ejb descriptor)
<p:pool>
<ejb-name>myEjbName</ejb-name>
<p:bean-instance-pool-ref>myPoolName</p:bean-instance-pool-ref>
</p:pool>