I think is possible.

The signal in CLK of 8251 pin must be higer than 30 times the TXC and RXC
Yo can obtain thouse frecuences with a divider i.e. 4040 from your system oscilator. The second cuestion is if you can obtain your baud rete from this frecuency.

I think you can obtain your clock signal from XTAL2 pin and then if you need some reduction get the CLK off 8251 from Q4 or Q3 and RXC-TXC from Q8 or Q9.

I think the other pins RD, WR, D0... are simple. Not?