Hi there does anybody know how to use versioning to build modules that are created for older kernel versions

Firstly I enabled the versioning support for 2.6.7 kernel and recompiled
Then I tried to seek the modversions.h file int /src/xxxx/includes/linux but I had no luck
On older kernel versions such as 2.4.20 a flag had to be used on gcc -DMODVERSIONS - include /xxxx/xxx/modversions.h if I'm not mistaken. Now on 2.6 kernel the .h file does not exist and compiling modules with gcc won't creat the .ko modules but the .o

Any help I really need to compile a cisco aironet driver for 2.4 kernel and on kernel 2.6 during complilation make gives me "unresolved symbol " errors I heard that versioning would help.
Please help
Thanx