Hi cjanow3,
Yes, this is possible. Owner is a special lookup field, and it is associated with these two tables: user and team.
So, if you want to filter both of these two tables. you need add two custom filter like this:
function addCustomerFilter(executionContext){
var formContext = executionContext.getFormContext();
var owner = formContext.getControl("ownerid");
owner.addPreSearch(applyFilter);
}
function applyFilter(executionContext){
var formContext = executionContext.getFormContext();
var owner = formContext.getControl("ownerid");
var customerUserFilter = "";
owner.addCustomFilter(customerUserFilter, "systemuser");
var customerTeamFilter = "";
owner.addCustomFilter(customerTeamFilter, "team");
}