I did a little research and found out that Lin is represented by super agent Scott Boras. Lin, along with fellow country-man Che-Yi Su were in the US earlier last year - March of 2004, where they showcased their goods in front of a ton of scouts in Chandler, Arizona. Obviously, scouts liked what they saw as Lin is now on his way to the US.
The guy over at baseballtaiwan.net has a pic up of Lin, Su, and Tsao. Here is the link. Lin is the guy on the far left, with Tsao in the middle, and Su on the right. From the pic, assuming that Tsao is 6'2" and Su is 6'0 even, I believe Lin stands somewhere around 5'10" to 5"11.
From what I've googled, Lin hasn't been on the international scene much as compared to some of the other recently signed kids. He was on the Under-17 Chinese-Taipei National team in 2001 that included teammates: Chia-An Huang(Mariners), Wei-Yin Chen(Chunichi), and Chien-Ming Chiang(Yomiuri). Lin was also included on the Taiwanese team that participated in the 2004 edition of the Grand Forks International Tournament.