I've been using cans like these (had a few from the race ATVs):
http://www.cyclegear.com/spgm.cfm?L1=&L2=&L3=&L4=&item=FTE_WUS_G
Using the cheaper model filler hose like these (or making one thats similar):
http://www.cyclegear.com/spgm.cfm?L1=&L2=&L3=&L4=&item=WES_28-1275
If you punch out...