Hi Sami - welcome to the site!
Jigging/popping for yellowfin are certainly not as popular here as it is in other countries like the USA. There, they seem to target yellowfin specifically with popping and jigging techniques. The little I've read is as you've set out below. Small, heavy jigs worked very quickly with a treble or single off the tail.
I tried this (unsuccessfully) in Vanuatu around a FAD. It feel very strange dropping a jig down when you know you will never hit the bottom!
I found this site while looking for information about GT popping as I go to Taveuni Island, Fiji by the end of Nov.
I happen to jig tuna including yellowfin regularly on the East Coast of the U.S..
The most popular technique for tuna jigging here is slow jiggigng by moving rods up and down in desirable depths. Though we jig them at the edge of canyon or deeper, you rarely catch them deeper than 100 meter and the prime depth you jig is 30 - 50 meter deep.
While you catch them longer or bigger jigs, you get more bites with smaller jigs. My preferred jigs are mostly 200 - 250 gram/ 15-20 centimeter though I've seen long jigs or bigger jigs work.
220g Seven Seas Hooker jigs work great for tuna.
The jigging techniques you use also work for tuna too. Tuna jigging here usually reguire longer hours and it is not uncommon we jig 10-12 hours non-stop to get a few bites on jigs as
tuna don't bite all the time and they sometimes just ignore jigs and you never know when they respond to jigs.
Many guys use treble hooks or single hooks, but assist hooks work as well.
I saw one member posted a tuna picture caught on a jig in South Africa. My next destination is Cape Town for jigging big yellowfin, probably Nov, 2008.