(uj) Splayed tables

Hi Gurus, 

Is it possible to somehow (uj) splayed tables? 

Say, I have just created and splayed table A. If I create and splay (or not) another table (table B) how can I union join them two (efficiently with good memory control - so I guess it will have to be done with the files on the disk, without mapping it into memory?) Memory control is important as the original table A will need to grow. 

Regards, 

Vadim A.