What would be the proper way to "register" the object myObject (which already exists) in another thread?
No way. You need to ask Gustaf to give you serialisation-code that you can use to replicate your object/classes blueprints from one thread into others as a matter of thread inits.
I can help out here: In order to serialize an object (in XOTcl, creating a canonical script from a in-memory snapshot of the given object, capable of creating an object and its dependencies with all the shebang), [package require] the serializer package which comes with your XOTcl distribution:
Class create C -slots { Attribute a1 -default aaa } -set x 1
C create c1
package req xotcl::serializer
# # this provides a new method to all ::xotcl::Object instances, i.e. all # objects -> serialize(): #
c1 serialize
-> ::C create ::c1 -noinit \ -set a1 aaa
the resulting script can be stored (e.g., in a tsv) and shared between thread interps. in the target interp, simply [eval] the script.
//stefan