Seeing as I'm in a good mood considering a couple failed coding attempts taking up the majority of my night...

powder.c in create_parts

if(t==PT_LASR)
{
float a = (rand()%8) * 0.78540f;
parts[i].life = 680;
parts[i].vx = 3.0f*cosf(a);
parts[i].vy = 3.0f*sinf(a);
}

float a = (rand()%8) * 0.78540f;
setting a to a random value, not my preferred method but this is a copy paste.

parts[i].life = 680;
Setting particle life to 680, it will decrease by 1 each frame until it reaches 0 when it will die.

parts[i].vx = 3.0f*cosf(a);
parts[i].vy = 3.0f*sinf(a);

vx and vy are used to control movement and are set using a load of math stuff I don't understand beyond Consine and Sine based on the random number set earlier
edit: What cracker said.