The footwell light thing really is that simple...if your car has the sockets, which apparantly most mk3 cars do.
Get a little mirror and look up midway along under the glovebox. You should see an empty bulb socket....simply fit the bulb.
Similar drivers side about level with the brake pedal.
Best of luck with it.
I have done a guide on fitting front and rear footwell lighting aswell as illuminated ignition ring,
Footwell lighting will be good if its as easy as it sounds I don`t really trust myself with wiring haha
See link on my profile page,
Guide to Fitting Footwell Lighting In Your Ford Click Here
If you don't have footwell lighting sockets currently there or would like to add any of the above i can link you to all supplies and instruct you on the process if desired.