What you want is - as far as I know - not possible.
But: You can achieve something very similar.

<tree string="Your Tree" editable="bottom">

Makes your one2many field editable in the list view. (also available: editable="top")

To make a column uneditable use the readonly tag:

<tree string="Your Tree" editable="top">
    <field name="your_field1" readonly="1"/>
    <field name="your_field2"/>       
    <field name="your_field3" readonly="1"/>
</tree>

This only field2 will be editable.