float fDegree = 0;
float fDegreeOffset = 0.1; //step
float fTimer = 0.022; //seconds
float fDistance = 2.5; //meter
vector vPos;
default
{
    state_entry()
    {
        vPos = llGetPos();
        llSetTimerEvent(fTimer);
    }
    timer()
    {
        llSetLinkPrimitiveParamsFast(LINK_THIS, [PRIM_POSITION, vPos + (fDistance*llSin(fDegree),llCos(fDegree),0>)]);
        fDegree = fDegree + fDegreeOffset;
        if (fDegree > TWO_PI)
        {
            fDegree = 0;
        }
    }
}