I found a way to register to Chikka Text Messenger while roaming overseas. Registration requires sending an SMS to a 4 digit chikka access code which will not work while overseas. Ideally, one would perform this registration setup before leaving the Philippines. But in case one forgets to do it, there is a workaround.
To get around this, install the Facebook Chikka lite app. Then put in your Philippines mobile number. That number will be sent a confirmation code. And after that you can use the lost password process to get a new password using the phone app.
The password will be sent to your mobile with a PHP2.50 charge. After that you are good to go.
Needless to say, it is necessary to have an active Philippines mobile number to register for Chikka Text Messenger.
For me, Chikka still has to be the best way to send SMS to the Philippines while overseas. Very convenient and best of all, free.