Online Forms and SuiteScript Customization

Hi there!
    I've run into an interesting use case which I hope somebody out there might be able to help me with.  I'm using an online form to glean potential sales leads through our website.  Everything works fine, a new lead is created from our online "contact us" form, etc., except the Addressee field in the customer record is null.  I suspect that this is because the Addressee field is sourced from the NLCOMPANYNAME field, when in fact, we're using the new individual customer records introduced in v.11 (our business is primarily a B2C model).
   As such, the NLFIRSTNAME and NLLASTNAME fields are filled out by the customer online.  I would like to develop a function to concatenate the two and populate it into the company name, or even directly into the addressee field on the customer record.  I'm pretty new to this stuff, so I'd like to know how I could accomplish this.  I'm thinking it'd probably be better to populate the field before it's submitted, but I defer to whomever knows better. :-)