Good luck, baffles the mind Yealink decided on those types of buttons in the first place, it's 2012.
Although, they have a sidecar for $140 http://yealink.com/index.php/Products/detail/id/16
that has electronic LCD buttons for t26, t28 and T38, but....again goofy to have to tell customer "use first 10 buttons as manual write-in entries but with the attached sidecar...its LCD!"
The T22 and this sidecar would make sense but oops, can't use with that model and it would make for a $225 phone.
Yealink T38 should have been all LCD, instead its like a nice new car with 4 small spare tires all around. Most businesses have LCD, we can't go and sell them these phones and expect them to write in speed dials or BLF do we? Hopefully their next model fixes this issue. T4X, where cost efficiency and technology merge!
Saw this Mitel phone the other day, pretty slick: http://www.mitel.com/resources/1206_6618-PN%2051015312RC-EN_lr.pdf, almost like an iPad touch screen. I think it is worth more then my car.