Tables and garbage collection

[Taylor Campbell <spam.address@dont.use>]

This is a bit more of a Scheme48 question than scsh in specific, but
since I already subscribe to this newsgroup and no Scheme48 mailing
lists, I might as well ask it here.

Is there any way in specific I should create a weak hash table, similar
to those in PLT, i.e., so when the garbage collector hits a certain
object in the table but not pointed to anywhere else it will garbage
collect it and remove it from the table?