Digital BW, The Print

What is a good way to remove a NMC CIS for a few days or a week?  I want to 
try some ink in cartridges and then replace the CIS.  I plan to plug up the 
cartridge holes with MIS rivets.  

At what height should I lay the cartridges relative to the bottles of ink?  
Sitting in the printer, the bottom of the carts are about equal height to the 
top of the ink bottles.  

And, should I store them with the rivets at the bottom facing down, like they 
sit in the printer?  Will they leak?  

Helene