How to Modify IP Header

["Robert Osborne." <roberto@corp.earthlink.net>]

Hello,

I am trying to create a program to modify the options field in the ip 
header for static routing under Open BSD.
I couldn't find any documentation regarding this type of modification.
Would I have to interrupt a kernel system call to write to the ip header?
Is there a book I can buy or any on-line documentation that will have the 
needed information to start this project?


Any information provided is much appreciated.

Thanks in advance
Rob