I am in the process of branching out from basic Arduino where I started, and I have been learning-by-doing through a fairly involved project using the AVR ATTiny841 uC.  In particular I found that IAR claims to have a significantly reduced size for the hex file and I have run out of space on the ATTiny841 and the chip cannot be changed.   

Is it possible to have VM use the IAR compiler to compile the sketch?  I have developed everything using the Arduino framework, but I like VM, and would like to try to use IAR compiler if possible to reduce the sketch size.  Please excuse my ignorance I am merely a hobbyist new to embedded system development.