How to set a _rec_name value through web client development?

I am using the web client for my development and wanted to know wether is was possible to set a _rec_name value through there. I have created a many2one field but the lookup shows the ids not a field value. Also through the web client you cannot create a name field as all custom fields must start with 'x_' How can I choose a field to display in the lookup instead of the id.