Will_Paginate, with muliple same type collection

Hi guys:
  i have a question about Will_paginate .

i have mutilple same type collections.
for example .

items_1 = Post.find(:all , :conditions =>{...}) # different condtions to
get the items_1

items_2 = Post.find(:all, :conditions ={...}) # diffenrt conditions to
get the item_2

items = items_1 | items_1

then how i am supposed to do in next step ?
please help

(the "Mark Ma" from Railsconf 07'?)