Actually Chicken does have the ability to tag objects as collision solids through Object Types.
Object Types are shortcuts for arbitrary bits of egg file syntax that are defined in your panda 3d .conf files. There’s a few of those that deal with defining collision solids so you can use those in Chicken for that purpose.
How to do that is explained in the manual, but for convenience I’ll explain here. You select your object, go to the logic panel (F4), and add a property named ObjectType, set its type to String, and give it a value corresponding to the object type you want (“sphere” for instance is one of the default types in Confauto.prc that defines a collision sphere). You can define additional object types in your Config.prc to do anything you want.
Also I should mention that any other property defined in this panel is exported as a Tag; that way you can export additional information with your models that you can use in your game logic.