Porting GL lookat command into OpenGL

I’m having problems porting the IRIS GL command lookat into the OpenGL gluLookAt.

The lookat work as:
lookat(vx, vy, vz, px, py, pz, twist)
where: vx, vy,vz are the coordinate of the viewing point,
px, py,pz are the coordinate of the reference point,
twist is the angle of rotation (measures right-hand rotation about the line of sight).

I need a way to convert the twist angle to the upX, upY, upZ values of the direction of the up vector in gluLookAt fonction.

Take a look at the code in Mesa, it is open source at sourceforge and you should be able to understand stuff from that.

I don’t know the IRISGL commands nor the gluLookAt to be able to explain much, sorry.