Update option set from text js

I have a script that gets fired from the Ribbon bar. It will create an entry in an other entity.

So far the only issue I have is one table has a text field the other is an option set. I am using XRMSERVICETOOLS.JS and if I manually add the value I can save the record.

What is the method for converting a text field to an option set when adding it to a new entity.

Thanks