As far as I understand by reading the data sheet, the RS-232 input lines are 5 volt tolerant. Apparently the chip has a pin (4) called vdd_232 which you can use to set the voltage of output-lines, which would protect connected MCU's tolerating 3-3.3V max. So, yes, it should be possible.
"RS-232 VDD. The RS-232 output signals (Pin 1 ~ Pin3) are designed for 5V, 3.3V or 3V
operation. VDD_232 should be connected to the same power level of the RS-232 interface. (The RS-232
input signals are always 5V~3V tolerant.) Note: This document version only provides 5V DC characteristic information. Refer to future revisions for updates. (Document Revision: 1.6
Document Release: April 26, 2005) "