Yes, it's been done many times. The Gen I bikes, which you must have, since Gen II bikes have LED indicators already, had optional LED Yamaha indicators available. The Yamaha kit came with load resistors to balance the load and keep the new blinkers from being very fast blinking. There are kits for that on ebay too. If you find some LED indicators you like, they will work, you just may need to add the resistors to slow the flash rate to 'normal'.
Load resistor - to give you an idea. I'm sure ebayUK has them too. LINK
Or use a LED flasher unit - FLASHER
Not sure if that is a direct replacement or not for the oem one.
I just did this last weekend on my 2012. I had those Yamaha LED blinkers sitting in a box for five years, but had the bike pulled apart for some other projects and decided to get to it. I used the Custom LED electronic flasher rather than the resistors and it all works great. It's an easy job, just takes a while since you have to pull a lot of bits off. Took me about four hours to install those and an Admore light bar, with lots of breaks and goofing off in there.
For what its worth, I've bought many 'affordable' aftermarket LED indicators, and none of them (save the expensive Rizomas) approach the Yamaha LED indicators that come on the 2014+ models. They are small, bright and very well built. If it were me, I wouldn't think about putting anything else on a Gen 1 Super Tenere.