Se você estiver usando a versão 4.8.02.0030 em um sistema de 64 bits e em um kernel 2.6.26+, deverá aplicar o patch fornecido por birdman. No meu caso, instalei com sucesso no Linux Fedora 9 rodando o kernel 2.6.25.14-108.fc9.x86_64.

1. Descompacte o VPN Client:

# tar xvfz vpnclient-linux-x86_64-4.8.02.0030-k9.tar.gz

2. Entre no diretório do client:

# cd vpnclient

3. Download do patch:

# wget http://birdman.dynalias.org/CiscoVPN/4.8.02-64bit.patch

4. Aplique o patch:

# patch < ./4.8.02-64bit.patch
patching file Makefile
patching file frag.c
patching file interceptor.c
patching file linuxcniapi.c
patching file linuxkernelapi.c

5. Após a aplicação do patch já é possível rodar o instalador:

# ./vpn_install

Se tudo der certo, a saída do instalador deverá ser parecida com:

Cisco Systems VPN Client Version 4.8.02 (0030) Linux Installer
Copyright (C) 1998-2006 Cisco Systems, Inc. All Rights Reserved.

By installing this product you agree that you have read the
license.txt file (The VPN Client license) and will comply with
its terms.


Directory where binaries will be installed [/usr/local/bin]

Automatically start the VPN service at boot time [yes]

In order to build the VPN kernel module, you must have the
kernel headers for the version of the kernel you are running.


Directory containing linux kernel source code [/lib/modules/2.6.25.14-108.fc9.x86_64/build]

* Binaries will be installed in "/usr/local/bin".
* Modules will be installed in "/lib/modules/2.6.25.14-108.fc9.x86_64/CiscoVPN".
* The VPN service will be started AUTOMATICALLY at boot time.
* Kernel source from "/lib/modules/2.6.25.14-108.fc9.x86_64/build" will be used to build the module.

Is the above correct [y]

Shutting down /opt/cisco-vpnclient/bin/vpnclient: module cisco_ipsec is not running.
Stopped: /etc/init.d/vpnclient_init (VPN init script)
Making module
make -C /lib/modules/2.6.25.14-108.fc9.x86_64/build SUBDIRS=/usr/local/src/cisco/vpnclient modules
make[1]: Entrando no diretório `/usr/src/kernels/2.6.25.14-108.fc9.x86_64'
  CC [M]  /usr/local/src/cisco/vpnclient/linuxcniapi.o
  CC [M]  /usr/local/src/cisco/vpnclient/frag.o
  CC [M]  /usr/local/src/cisco/vpnclient/IPSecDrvOS_linux.o
  CC [M]  /usr/local/src/cisco/vpnclient/interceptor.o
  CC [M]  /usr/local/src/cisco/vpnclient/linuxkernelapi.o
  LD [M]  /usr/local/src/cisco/vpnclient/cisco_ipsec.o
  Building modules, stage 2.
  MODPOST 1 modules
WARNING: could not find /usr/local/src/cisco/vpnclient/.libdriver64.so.cmd for /usr/local/src/cisco/vpnclient/libdriver64.so
  CC      /usr/local/src/cisco/vpnclient/cisco_ipsec.mod.o
  LD [M]  /usr/local/src/cisco/vpnclient/cisco_ipsec.ko
make[1]: Saindo do diretório `/usr/src/kernels/2.6.25.14-108.fc9.x86_64'
Copying module to directory "/lib/modules/2.6.25.14-108.fc9.x86_64/CiscoVPN".
Already have group 'bin'

Creating start/stop script "/etc/init.d/vpnclient_init".
    /etc/init.d/vpnclient_init
Enabling start/stop script for run level 3,4 and 5.

Installing license.txt (VPN Client license) in "/opt/cisco-vpnclient/":
    /opt/cisco-vpnclient/license.txt

Installing bundled user profiles in "/etc/opt/cisco-vpnclient/Profiles/":
* Replaced Profiles: sample

Copying binaries to directory "/opt/cisco-vpnclient/bin".
Adding symlinks to "/usr/local/bin".
    /opt/cisco-vpnclient/bin/vpnclient
    /opt/cisco-vpnclient/bin/cisco_cert_mgr
    /opt/cisco-vpnclient/bin/ipseclog
Copying setuid binaries to directory "/opt/cisco-vpnclient/bin".
    /opt/cisco-vpnclient/bin/cvpnd
Copying libraries to directory "/opt/cisco-vpnclient/lib".
    /opt/cisco-vpnclient/lib/libvpnapi.so
Copying header files to directory "/opt/cisco-vpnclient/include".
    /opt/cisco-vpnclient/include/vpnapi.h

Setting permissions.
    /opt/cisco-vpnclient/bin/cvpnd (setuid root)
    /opt/cisco-vpnclient (group bin readable)
    /etc/opt/cisco-vpnclient (permissions not changed)
* You may wish to change these permissions to restrict access to root.
* You must run "/etc/init.d/vpnclient_init start" before using the client.
* This script will be run AUTOMATICALLY every time you reboot your computer.

Em caso de algum problema, recomendo acessar o fórum do Alexandre Griesser.