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Sugimori inks all of his outlines then colors them in on the computer (or at least did as of FRLG, pic related), so one way to imitate the linework is to outline your art by hand then scan it in.
However if you're limited to just the computer the outline style can easily be replicated even with the regular pen tool as long as you're working at a large enough size. Keep your linework somewhat loose and then when the piece is finished you can blur the outline either with a blur tool/effect or just resize the piece to about 90% and it'll soften the edges for you, depending on your settings.
There are guides out there to imitating the style if you look around. Ultimately it all comes down to studying his work (seeing when he uses certain shading, highlights, etc.) and practice.
