From my custom beans I usually use the WizardServices API to maintain properties. From a WizardBeanEvent parameter, you can do
Then, from wherever you have access to a WizardServices object, you can retrieve the property.
If you need to resolve the property someplace where you can't use code (ie, in a Rgy import action attached to a component), look into the product services API to set a property on the product bean. Something like this would work:
Then you can use $P("productBeanName"."propName") to resolve the property value.
ProductService prodService = (ProductService)arg0.getService(ProductService.NAME);
prodService.setProductBeanProperty(ProductService.DEFAULT_PRODUCT_SOURCE, "productBeanName", "propName", "propValue");