Instead of the standard cone and point lights you can use a light 
shader, basically a custom coded light. Houdini ships with several special lights, most of them coded in VEX.
Using light shaders
Create a light shader in the network editor at the
Shader level using the tab menu.
Shaders, including light shaders, are specific to the renderer you will use. Shaders whose names start with
VEXwill render in the Houdini’s standard
mantra renderer. Other shaders work
in other renderers (
RenderMan shaders start with RMan,
mental ray shaders start with MI).Create a
Light Template in the network editor at the Object level using the tab menu.
In the parameter editor of the light template, assign the light shader you just created as the Light Shader on the Shaders sub-tab of the Render tab.