The best way to get them in and get everything situated is to remove the housing completely and utilize a workbench or kitchen table. The rubber grommet can be a real PITA to get situated. Depending on the condition of the factory rubber boot on the back of the housing, you MIGHT have to make a small relief cut or two, but with enough finesse it should go right in. Good luck!
Last some time? You must be running/have run a 35W kit. I had the 55W DDM kit with 8000K bulbs and they lasted just about 6 months to the day before one finally burnt out. It started dimming after about 5 months. I switched to 6000k for the new bulbs and I made it about 5 months before switching back to halogen. Both bulbs were just starting to show signs of needing replaced too, so it was perfect.