Hi Nicola,
Basically what I put in the email were the following links...

Craig Reynolds ( Excellent site ) - http://www.red3d.com/cwr/steer/

Steering Behaviors For Autonomous Characters - http://www.red3d.com/cwr/papers/1999/gdc99steer.html

AI used in Colin McCrae - http://www.ai-junkie.com/misc/hannan/hannan.html

AI Madness: Using AI to Bring Open-City Racing to Life - http://www.gamasutra.com/features/20.../adzima_01.htm

OpenSteer - http://opensteer.sourceforge.net/

The BEST place to start for this sort of thing is Craig Reynolds page and he is one of the original guys ( IIRC ) who formalised steering an flocking behaviour, in terms of algorithms. The Colin McCrae AI and AI Madness articles are also very interesting.

Lastly OpenSteer is an opensource implementation of steering behaviour, I have not looked into it, but may be they have a C interface that Pascal can interface to.

I hope you find this usefull.