How to set static IP when installing coreos from USB-stick?

Hi,
I'm trying to install fedora coreos on my server. I do not have a DHCP-server
available but used static IP before (project atomic).
When booting coreos from USB-stick it is looking for a DHCP-server. When not found it
fails. After a while it retries to get an IP-address.
I have tried to add a lease command to /etc/dhclient.conf like:

lease {
  interface "eth0";
  fixed-address 192.168.5.50;
  option subnet-mask 255.255.255.0;
  option routers 192.168.5.10;
  option domain-name-servers 192.168.5.10;
}

Then I killed the dhclient process and restarted it with same parameters as it was run
before:
dhclient -4 -q -cf /etc/dhclient.conf -pf /tmp/dhclient.eth0.pid -lf
/tmp/dhclient.eth0.lease eth0

But dhclient does not use the static configuration I have made and fails with a message
like:
Could not find a valid lease.

What am I doing wrong here? Is there an easier way to force a static IP address? Can I
stop the boot process and give some commands when loading the kernel?

Any ideas appreciated.
Best regards,
Jonny

Doug H proposed the following which solved the problem for me:

For one time only command line addition it should look something like
this:

Check current state...

[root@localhost ~]# cat /etc/resolv.conf
# Generated by NetworkManager

[root@localhost ~]# ip route

[root@localhost ~]# ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN
group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: enp0s3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel
state UP group default qlen 1000
    link/ether 08:00:27:ca:d8:42 brd ff:ff:ff:ff:ff:ff
[root@localhost ~]#

Use interface "enp0s3"...
(The device, network used, ip used and default route must be what would
work for your setup)

[root@localhost ~]# echo "nameserver 8.8.8.8" > /etc/resolv.conf

[root@localhost ~]# ip addr add 192.168.1.5/24 dev enp0s3

[root@localhost ~]# route add default gw 192.168.100.254 enp0s3

Verify...

[root@localhost ~]# ping -c2 google.com
PING google.com (172.217.14.206) 56(84) bytes of data.
64 bytes from sea30s01-in-f14.1e100.net (172.217.14.206): icmp_seq=1
ttl=55 time=38.0 ms
64 bytes from sea30s01-in-f14.1e100.net (172.217.14.206): icmp_seq=2
ttl=55 time=38.7 ms

--- google.com ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1001ms
rtt min/avg/max/mdev = 38.019/38.379/38.740/0.360 ms
[root@localhost ~]#
-- 
Doug H.