Visual Studio :: Retrieving Values Using Ienumerable Interface

I have been founding an effiecent way to retreive values returned by LINQ 2 SQL stored procdure on my presentaion layer. Am using following method rightnow:-

public List<String> MthInvitesBA()
{
List<String> lst = new List<string> { "" };
ISingleResult<USP_Actor_View_InvitesDetails1Result> invites = obj.USP_Actor_View_InvitesDetails1(p_UserName);
foreach (USP_Actor_View_InvitesDetails1Result c in invites)
{
lst = new List<string> { c.Invites_Used.ToString(), c.NoOfDoc.ToString(), c.Request_For_More_Invites.ToString() };
return lst;
}
return lst;
}

It works but at the cost of my performence due boxing unboxing on BA layer as well as on design layer. Now, I have one method which returns me 100 columns from table So in this way i have convert 100 coulmns value into type string then On design layer again have to type caste some values .Moreover, i could only access this list using index which is of type integer, which is very diffcult and tedious task to debug d code. i could effiecenlt retreive these values. Is it possible using IEnumerable? How to access Ienuemerable in design layer?