The original example proceeded via sequential loss of two equivalents of H from decamethyltungstocene dihydride, Cp*WH.  The first dehydrogenation step affords a simple tuck-in complex: 
:(CMe)WH  →  (CMe)(η-CMeCH)WH  +  H
The second dehydrogenation step affords a double tuck-in complex:
:(CMe)(η-CMeCH)WH   →  (CMe)(η-CMe(CH))W +  H
In organouranium chemistry, both tuck-in and tuck-over complexes are recognized, for example in the dihydrido diuranium complex  [Cp*(η-CMe(CH))UH].  In this complex the two methylene groups bind to different uranium centers. The tuck-over mode is binding of the Cp* methylene to a metal center elsewhere in the molecule rather than the one coordinated to that Cp* ligand.