Shopper field custom field in a plugin

[giugio]

hello.
I wish create  a plugin or a component for virtuemart 2 that insert a custom Shopper Field in the Shopper Field List menu in virtuemart , now is sufficent a text field with a custom validation(i must test a my valid code, is a little complex to explain).
Then
1)create a plugin for virtuemart2 that adds the custom field, this is usefull for deployment because is sufficent to install the plugin and voila added have a new custom field(but is possible??)
2)a server side validation method with php for my custom field.

thanks.