How to set custom Option set on Runtime?

Hi,

I want to create a custom option set with check box available to options on 'onload' event of the entity.

Also i need DISTINCT data which can be used as options to this option set.

Using of odata is not possible as we cant use 'distinct' in it and also there is a limitation of retrieval of 50 records only.

Please suggest me what can i use to retrieve distinct values from 7k+/10k+ records through javascript. (Needs to execute this JS onload of entity).??

And how can i assign this distinct values to option set on runtime with checkboxes???