It's doable as there are many tutorials/YouTube videos about it already.
The hard part is to "tweak" the 24-pin connector as you need a splitter (not recommended) or a circuit like add2psu.
Just search add2psu or similar circuit on amazon/ebay. It works with multiple PSU.
I would not look for such circuits on YouTube, but would buy a proven adapter. But it’s better to either reduce the number of video cards or increase the power of power supplies so as not to create unnecessary problems for yourself. I buy a new power supply for each mining farm and do not save money on this.