Unfortunately it does not appear that the jtds driver will support this.
From a quick review it appears that the AlwaysOn Availability Group was introduced recently, and is only available through their JDBC 4.0 driver: JDBC Driver Support for High Availability, Disaster Recovery
Where the jtds driver is built with the 3.0 MS JDBC driver as the baseline and does not have the option to set the required options: multiSubnetFailover, and applicationIntent
jTDS JDBC Driver
I am going to verify this internally and will let you know.