Hi Niro,
Not sure if this helps, but I've run some cabling through for a ham radio, and am planning to run another through the same way for my pda too.
What I did was to remove the centre rubber tray on the top of the dash. I think this is sometimes a cupholder on newer models, not sure though. If it's like mine, it will just pop out if you pull it. Underneath should be a square hole about 1cm square or so. I increaed the size of this hole to accomodate the size of the power and antenna plugs for the radio. I fed the cables through and found that by lying upside down in the passenger side footwell, I could get my arm up and around the back of the dash to grab the end of the cables (from underneath). I pulled them through and secured them with zip ties on the way down. Personally, I ran the power cables under the gearstick/handbrake housing right through to the rear power socket, which i connected into to get my power feed. I removed the inside of the rear ashtray and used the remining hole/cover to house the inline fuses, which I though was neat.
Not sure if you do anything similar with your power cables? Perhaps you might want to consider buying one of those x3 12v socket adapters, cutting off the plug and wiring it into the rear power socket as above, then leaving the 3 sockets tucked up behind the dash with your pda/gps power leads plugged into it?
Hope this is of some use!
James
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