How do proponents of the Prosperity Gospel interpret Matthew 6:19-21 and Luke 6:20-26? There is already this decent post: What is the argument *for* prosperity gospel? But more specifically how do prosperity theologians square what must be regular 'clobber' passages for their interpretation? 

For example:


  Do not store up for yourselves treasures on earth, where moths and vermin destroy, and where thieves break in and steal. But store up for yourselves treasures in heaven, where moths and vermin do not destroy, and where thieves do not break in and steal. For where your treasure is, there your heart will be also.
  Matthew 6:19-21 (NIV)


And:


  Looking at his disciples, he said:
  
  “Blessed are you who are poor,
      for yours is the kingdom of God.
  Blessed are you who hunger now,
      for you will be satisfied.
  Blessed are you who weep now,
      for you will laugh.
  Blessed are you when people hate you,
      when they exclude you and insult you
      and reject your name as evil,
          because of the Son of Man.  
  
  “Rejoice in that day and leap for joy, because great is your reward in heaven. For that is how their ancestors treated the prophets.
  
  “But woe to you who are rich,
      for you have already received your comfort.
  Woe to you who are well fed now,
      for you will go hungry.
  Woe to you who laugh now,
      for you will mourn and weep.
  Woe to you when everyone speaks well of you,
      for that is how their ancestors treated the false prophets.
  Luke 6:20-26 (NIV)
And why do you worry about clothes? See how the 
  flowers of the field grow. They do not labor or spin. 
  29Yet I tell you that not even Solomon in all his 
  splendor was dressed like one of these. 30If that is 
  how God clothes the grass of the field, which is here > today and tomorrow is thrown into the fire, will he 
  not much more clothe you—you of little faith?  
  
  Matthew 6:28-30


Addressing the Matthew 6 verse, if you take an anti stuff position in v19-20,  how do you handle v28-30, above?

God clothes the grass better than even Solomon dressed Himself.  And, at a face value reading of v30, it says He will "much more" clothe us, apparently compared to the grass itself.

v18-19 is talking about storing up and treasure.  These are both qualities of the heart, and so the emphasis is on a covetous attitude, not having things. 

The Luke passage is likewise more concerned with a willful blindness of heart.  It is not primarily concerned with "stuff".  This is shown by verses such as John 6:63 and Mark 10:30.  Of course, that is also its own balance--while prosperity can be seen in the NT, people should not be "money minded".  Even the late Kenneth E. Hagin, "father of the Prosperity Movement", said as such, and wrote "The Midas Touch" as a warning / exhortation against taking such preaching where it should not go.