VMware: Adding a static route to an ESX host for an extra service console
First you can add a route with putty or console:
route add -net 172.16.254.0 netmask 255.255.255.0 gw 10.20.1.222
After restart your route is gone, so you need to add a static route.
Add the following line to /etc/rc.local so that route is set on boot:
/sbin/route add -net 172.16.254.0 netmask 255.255.255.0 gw 10.20.1.222
Source: VMware KB