WV GOLF ATF

I just purchased a 2002 WV Golf and was performign some DIY
maintanance. I want to change the ATF, filter, and the gasket. I was
wondering if you can do it yourself in a garage for the dealers claim
you can't because you need special tools, especially to measure the
temperature under which to place the oil in. After consolting with the
dealers, who themselves were not sure if I sould even change it, two
said that I should but only in the shop (for approx. $500)! My
question is therefore, can I do it myself or should I take it to the
service. If so, can you give me some guidelines for proceeding for I
never dealt with this "closed system" B.S. for ATF.

Vlad