I found the 5.4 documentation here:
https://www.juniper.net/documentation/software/screenos/screenos5.4.0/
For the proxy arp it looks like the screenOS 5.4 command is this.
set arp always-on-dest
For the source routing, the match on source needs to be assigned to the interface for the internal address while the outbound address is to egress interface eth4. We changed the egress interface from the eth1 to eth4 but I did not notice the bind interface for the source address was also to the egress interface eth4 and not whatever interface has the 192.168.0.45 address.
ScreenOS 5.4 routing page 132
https://www.juniper.net/documentation/software/screenos/screenos5.4.0/ce_v7.pdf