I've always been majorly impressed with Romeo's usage of legato in riffs on the lower strings. Very punctual, well defined, very even and it always just plain sounds fucking
examples... the riff in Sirens (the oddysey), some riff parts in wicked, in evolution, in king of terrors. there are lots more examples too. And what about a certain riff from the end of Walls of Babylon (which is of course a major part of many of the riffs throughout)? how can you not to that one?
The way I do it is I just fingerpick it like normal, but it has to be really articulate to get it sounding right. For the Ab, I just change it a bit. I slide my left hand up (I'm playing fretless) and then tap the Ab with my right hand and then tap my middle finger on the left hand just before. And then alternating for four quick taps.