databound checkboxlist on prerender_completed event

Hi!
When playing around for testing with creating dynamic controls, i had a checkBoxList with a collection of items... and depending the item selected, the web app creates the appropiate controls... so far so good.
Now, moving to the "real" project, i have the same scenario, with a little change: the checkBoxList is bound to a database and receives an id from the previous page... So, once the elements are added to the chkBxLst, i loop throgh the chkbxlst finding elements related with the received id to set their "selected" property  to true. This has to be done in the preRender_Completed event, because i can not loop through the chkbxlst in the load or init event ('cause they dont exist yet). So far so good.
Here's the thing, as i loop through it on prerender, i'm force to create the dynamic controls henceforth... cannot do that until some elements are checked... and, by doing that, the web application creates the dynamic contro ...