Two users will be accessing one elist item having the write access to the elist and the same users will be accesing different two cubes but for one user must have read access for one cube and write access to another cube for another user viceversa
I'm not completely sure I understand the final requirement, you have 2 users that need to be able to read/write to 2 different cubes, and vice versa...
Regardless, I'm not sure that you can accomplish this. Access tables would be the way to go, but they apply to elist items as a whole, so you wouldn't be able to assign different rights to the 2 cubes for the 2 unique users.
You might be able to create a separate elist item for one of the users. Then use an admin link or system link to populate a summary cube or summary application.
If anyone knows of a way to accomplish this I would be interested to see how.
We had this requirement before and the answer was user education, making sure they communicate with each other about when they are going into that elist item. Going down the road of individual elist items for specific users can get messy fast. I had inherited an app that was designed that way and I took it away in favour of user education. Everyone is happier now and things run better as well.