My 53 plate uk 350 has the same sun visor bulbs as the import models . As CS2000 has already pointed out to people they are soldered in so not easy to covert to LED
Anyway it's been bugging me since changing all other interior bulbs to LEDs so here's what I've come up with;
I bought some festoon LEDs http://www.ebay.co.uk/itm/281052978818?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649
Then I pulled them apart which was easy as they were not soldered together
In the car I stripped the plastic cover off the visor light to reveal the bulb and switch plate.
The switch plate is what the bulb is soldered to and it just unclips with a bit of a pry from a small flat screw driver.
This is the switch plate but with the new LED in place (forgot to get enough pictures!)
Then it's just a case of un soldering the original bulb and soldering in the new LED, it's very straight forward really just make sure you install the LED the correct way round else it won't work !
Then put it all back together and you should end up with this
I hope that helps someone else with the same visors as me and if you need any help PM me