Just so you know Debian is not supported under VMware Fusion however not supported and will it work are two different things and while only generally speaking here, not supported means that you usually have to do some extra things to make it work aside from just installing the OS and installing VMware Tools and even then some features may not work. Here is what was needed to enable installing VMware Tools and to have its features working, especially having VMware Shared Folders HGFS Share accessible and the Mouse grab/ungrab automatically and what I'd call a complete and successful install.
Download the debian-501-i386-CD-1.iso ISO Image (you only need the first one to get going) then create an Other Linux 2.6.x kernel Virtual Machine using the New Virtual Machine Assistant. Note that as you walk through the wizard and get to the Finish sheet do not click the Finish button however click the Customize Settings button and save as Debian 5.0.1 and then the Debian 5.0.1 Settings window opens and make any changes to the default settings that suite your needs/wants and if you're going to use VMware Shared Folders then set it up now under Sharing before installing Debian. Note that enabling Sharing and setting a Shared Folder is not absolutely necessary to be done ahead of installing but it eliminates error messages during the install of VMware Tools and rebooting and is therefore less confusing in the long run.
After the OS install is complete and now at the Debian Desktop use the Synaptic Package Manager (Top Panel: System > Administration > Synaptic Package Manager) to install the following packages (along with the noted dependencies) however first change the Repositories to not use the CD-ROM (Synaptic Package Manager: Settings > Repositories > Third-Party Software tab and uncheck the "cdrom: ..." check boxes.) and then click the Reload button. Note: If the Kernel version you're using is different then use the appropriate version value where applicable. Executing "uname -r" in a Terminal (without the quotes) will display the Kernel version.
gcc-4.1 linux-headers-2.6.26-2-686 make
After installing these packages then click Install VMware Tools from the VMware Fusion (menu bar) > Virtual Machine menu and this should open a window to cdrom0. Now extract VMware Tools to the /tmp folder by right-clicking the VMwareTools-7.9.3-159196.tar.gz file and selecting Extract To... then select File System under Places and then select tmp under the Name column and after the extraction is finished then unmount the CD-ROM by right-clicking the VMware Tools CD Icon on the Desktop and select Eject.
Next use a Root Terminal (Top Panel: Application > Accessories > Root Terminal) to do the following before installing VMware Tools...
Note: All remaining steps take place in this Root Terminal.
Hint: You can copy and paste these commands, as is, if you access this thread from a Browser in the Debian Virtual Machine after installing the OS.
Create a symlink to the Linux Headers using the following command:
ln -s /usr/src/linux-headers-2.6.26-2-686 /usr/src/linux
Next change the gcc version to be used to 4.1 using the following command:
export CC=/usr/bin/gcc-4.1
Next change to the VMware Tools Distribution folder using the following command:
cd /tmp/vmware-tools-distrib
Note: With the exception of selecting the display size the remaining prompts can be answered by just pressing Enter to accept the defaults.
Next start the VMware Tools install using the following command:
./vmware-install.pl
After the VMware Tools install is finished then edit the following two files: /etc/fstab and /etc/X11/xorg.conf
Note: When using nano to edit these files use the arrow keys to move around and then Ctrl-O (O) to WriteOut the changes and then Ctrl-X (X) to Exit.
Next backup and edit the /etc/fstab file using the following command:
cp /etc/fstab /etc/fstab.backup; nano /etc/fstab
Add the following directly after "defaults,ttl=5". Note: This assumes this being done under the first User Account that was created and if under a different User Account then in a normal Terminal (Top Panel: Application > Accessories > Terminal) type $ then press Enter and the numeric value returned is what you'd use in place of 1000 for both the uid= and gid= numeric values.
,uid=1000,gid=1000
So it looks like:
.host:/ /mnt/hgfs vmhgfs defaults,ttl=5,uid=1000,gid=1000 0 0
Next backup and edit the /etc/X11/xorg.conf file.
cp /etc/X11/xorg.conf /etc/X11/xorg.conf.backup; nano /etc/X11/xorg.conf
Add the following line in the "Section "InputDevice"" for the "Identifier "VMware Mouse"".
Option "CorePointer"
So it looks like:
Section "InputDevice" Identifier "VMware Mouse" Driver "vmmouse" Option "CorePointer" Option "Device" "/dev/input/mice" Option "Emulate3Buttons" "true" Option "ZAxisMapping" "4 5" EndSection
Now reboot the Virtual Machine and you should now have a Debian 5.0.1 Virtual Machine with VMware Tools installed and the Mouse grabbing/ungrabbing automatically.
Note: If I can find the time I'll write a shell script to facilitate the installing of the needed packages, VMware Tools and modifications to fstab and xorg.conf along the lines of the shell script I wrote for installing Ubuntu 9.04 in however at the least these directions are simple enough that it shouldn't be to hard for you to enjoy a fully functional Debian 5.0.1 Virtual Machine in VMware Fusion 2.0.4. 
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WoodyZ - VMware vEXPERT 2009
