Step 1: What You'll Need.
Soldering iron + Solder
Standard frosted bulb bayonet cap BC(frosted glass as opposed to powderd)
Hot glue gun
Jet flame lighter
4 or so white LEDs
Desk lamp (with BC bulb fitting, you can swap out the screw thread type to this)
AC/DC adaptor that has the same output as your LEDs, i used one i had lying around if you don't have one pick one up off eBay
Step 2: Open the Bulb
Ease the cap open DO NOT JUST PULL it off, it should still be connected by two thin wires cut these with scissors near to the top and leave connected to the base.
I forgot to do this and it caused a lot of hassle later on.
Step 3: Cracking the Bulb
The best way I have found to do this is by using the cutting disk on the dremel to press lightly onto the glass surface to leave a mark, keep it there and a crack should appear. Using the cutting disk you can extend and change direction of the crack until it encircled the bulb and the top comes off.
Step 4: Dulling the Edges
Now the top of the bulb is off you probbily not want sharp edged on it so take your jet lighter and the edges until they go clear. this has the added bonus dof making the edge slightly thicker and less likely to break.
I tried doing this with a small blow torch but the flame was too hot and caused the glass to shatter so i returned the my lighter.
Step 5: Making Space for the LEDs
Step 6: The LEDs
Step 7: The Base
Step 8: Sealing the Bulb
Step 9: The Desk Lamp
Next i cut the existing lead off the lamp and attached the connector for the AC/DC adaptor and hot glued it into the gap the cable ran into.