Hi
I think there was another question recently along the same lines...
If you use a text field rather than a select in the form settings. Then use an asseting listing to dynamically generate the options.
If you hardcode the select field in and use the name/assetid that corresponds to the text field in Matrix then it should work.
Depending of the specifics of the form (eg validation) you may want to add some javascript to control the front input and regex rules to control what can be save to the text field.
Thanks
Peter