WMS client and reprojections

[Nuno Gil]

Dear listers,
I am trying to use a cascaded dataset available in a specific
projection (lets say projection A).
The server that is serving that dataset is unable of reprojecting data
on -the-fly and I need that data in projection B to be server through
MapServer. Is it possible for Mapserver to reproject cascaded layers?
How can I do this? I have already tried to specify the original
projection (A) in the map file (inside the layers definition) and
requesting the data in my output coordinate system (B) but I receive
an exception saying that the SRS is not supported.

Regards,
Nuno