Don't know of a Linux tool for MS SQL.
However, if you have SQL runnning on Windows 2000 Server, you could load Terminal Services in remote administration mode.
You could then use the Linux terminal server client to access the SQL box. I know of someone who uses Enterprise Manager remotely from a Windows 2000 Professional machine. I have never used the Linux client so you would have to test it yourself.
According to Sys Admin Magazine, November 2002, the Linux client is available at rdesktop.org. The article is a good one. You can check sysadminmag.com to request a reprint if the article is not online.
I read a post late last week that suggested that the client came with Red Hat 8.0.