hi,

I have look mode 0 in 8051, but its'n posible to modify baudrate in this mode.

sure for standard 8051 derivatives. But there are alot of modern parts which allow you to modify the shift register baud rate. For example, AT89C51RD2 has internal baud-rate generator which may be utilized as for mode 1 and 3 as for mode 0.
Another question is that this mode may not be useful for your application. What I may suggest is the usage of software emulated receiver. For speed 19200 it takes about 52μs for a bit transfer. So I see no problems to utilize a timer or PCA channel to receive data stream.

Regards,
Oleg