Hi,
To compute your own boundary conditions in TELEMAC-2D, you can implement your source code directly in BORD subroutine.
You have 3 examples of how to implement tidal boundary conditions in BORD_TIDE, BORD_TIDE_LEGOS subroutines and the TPXO module. Another subroutine that may help you is TIDAL_MODEL_T2D called in BORD subroutine with condition.
Otherwise, in this forum, other users have already posted the same questions...
Hope this helps,
Chi-Tuan