I found a solution using just the watch mechanism of C::B. Actually gdb will execute
where "..." is the content of a line of the watch file. For example when variables toto, blabla, ole are watched, the content of the watch file is
Now, it is possible to add more arguments in the watch file, or read absolute addresses instead of symbols. For example output /x (my_type)*0x1234 will read at address 0x1234 and interpret it as a variable of type my_type in hexadecimal. Subsequently it is possible to read remote content by 1) defining a structure containing the remote registry (let say msp430_regs_t in my case) 2) adding in a default watch file
/x (msp430_regs_t)*0xXXXX
where 0xXXXX is the registry base. I checked that this is correctly interpreted by C::B.
Regards, Yordan