1:set route 192.168.240.0/24 gateway 10.152.4.25. This will forward traffic to 10.152.4.25 which is destined to 192.168.240.0/24.
2: however, 192.168.240.0/24 will be your source addresses not the destination addresses, right?
3: the command should be "set route <destination IPv4 Address/Netmask> gateway 10.152.4.25" , use 0.0.0.0/0 as destination address if you want everything to go to the 10.152.4.25.
check KB http://kb.juniper.net/InfoCenter/index?page=content&id=KB5712&actp=search , you can add interface also in the static routes.
Thanks,
Vikas