I am not a hardware wizz... but i seriously doubt it...
If you put it in serial you will run the same task/process four times. and thus reduce performance. In parallel amiga os (i guess) would see only one cpu and crash when four cpus tries to do the same thing...
However separating them on the fsb and giving them a separate cpu bus may work
But still the os has to support multi cpus at first.
And i don't think amiga os is capable of doing so....