For anyone interested:
To make a transfer from a secondary base ( in my case from 1st Flotilla in Brest to 23rd Flotilla in Salamis):
1. I begun a new false campaign in Salamis
2. I opened the file in C:\Documents and Settings\Admin\Mes documents\SH3\data\cfg\Careers\*** and copied in my true campaign from the false Careers_0.cfg the next items:
CrtBase=763
CrtPort=13
PortName=Salamis
With these modifications, I could open my true campaign (always 1st Flotilla in Brest) and made the transfer to the 23rd Flotilla in Salamis.
Cheers