I haven't tried it, but Barry's book claims it will work if you're running 4.0 or later.
TMCC Lashups
DCS release 4.0 allows the creation of lashups between two or more TMCC engines. The process of creating
a TMCC Lashup is identical to that of creating a lashup of DCS engines, with the exception that the Create
TMCC Lashup menu entry is selected. When the lashup is created, it will be assigned the first available DCS
ID# in the range 91 through 99. This will equate to a TMCC Train number of 1 through 9. TMCC lashups are
subject to the following rules:
• If there is not an available DCS ID# 91 through 99, the lashup creation will fail.
• If the same lashup is created in more than one DCS Remote, the lashup's DCS ID# and therefore its
TMCC Train number must be the same in all DCS Remotes in which the TMCC lashup appears. If not,
only the last occurrence of the lashup that was created will operate from the DCS Remote in which it
was created.
• A TMCC engine may not be a member of more than one TMCC lashup. If it is, only the last TMCC
lashup in which the engine was included will be able to be operated.