Actually you can use any 9-speed Shimano shifters with your D-A 8-speed as long as you are also using the D-A 8-speed rear derailleur. Shimano 9-speed shifters have the same cable pull as 8-speed D-A. The D-A rear derailleur actuation ratio is unique.
Do not use the alternate cable routing with this setup.
It's all explained on this chart:
http://www.ctc.org.uk/DesktopDefault.aspx?TabID=3946 Scroll down to Shimano mechs.
I don't know about the microshifter cable pull, but I do not believe you would want Shimano 8-speed microshifters. If the Shimano 9-speed Microshifter has the same cable pull as the STI 9-speed shifter it should work with your D-A 8-speed rear derailleur.