Of course you can, but it would be the same as trying to clean the bathroom with a toothbrush.

The 8051 was simply not designed for multitasking (no supervisor mode, only 8 bits, a little sloooooow, and not designed for loading arbitrary programs into RAM and running them from there).
You smell like one of those types who want to do microCOMPUTER things with a microCONTROLLER, but no offense ;-)

As a friendly piece of advice: developing a sense of how to make good ENGINEERING CHOICES is a lasting asset. Ask yourself: I want to clean the bathroom. What would I need to do that efficiently? NOT I know toothbrushes. Could I use one to clean the bathroom?
It's the road to a successful carreer as an engineer.