This short guide allows you to install SAP GUI Java on linux sistem (I tested on Squeeze/Testing):

  1. Java Runtime Environment installed on your system.
    On Debian Squeeze and Ubuntu Koala I suggest you to use Sun Java JRE

    $ sudo aptitude install sun-java6-jre sun-java6-plugin sun-java6-fonts

    check your version using

    $ java -version
java version "1.6.0_16"
Java(TM) SE Runtime Environment (build 1.6.0_16-b01)
Java HotSpot(TM) Server VM (build 14.2-b01, mixed mode)
  2. Download SAPGUI
    ftp://ftp.sap.com/pub/sapgui/java/ (anonymous login)
    https://service.sap.com/sapgui-java (OSS user and pass)

    currently rev10 is available PlatinGUI-Linux-710R10.jar

  3. In the downloaded folder, execute 
    $ java -jar PlatinGUI-Linux-710R10.jar

    in Other section of Gnome menu now you will have the SAP GUI shortcut.

  4. Add a new system connection
    At SAP Logon select New->Advanced and insertconn=/H/url.to.sap.system/S/32xxinstead of xx insert the system number.
    From command line you can execute:

    ~/SAPClients/SAPGUI7.00/bin$ ./sapgui /H/url.to.sap.system/S/32xx

Next, SAP Gui using wine…

Refer to OSS Notes for further info