I've succefully compile kernel 2.6.35 to a imx28 target and want to test 8021q feature.

I found some documentation on creating vlan but I'am misses vconfig commands.

Me guess it that I'am missing a software package?

it would help to know what distribution you are using

but as a fast fix, you could build the sources from this list of instructions

mkdir /tmp/vlan
cd /tmp/vlan
wget http://ftp.bit.nl/mirror/slackware/s...an.1.9.tar.bz2
tar xf vlan.1.9.tar.bz2
make clean
make vconfig

(you can use the vconfig from here, or if you feel sure just use the next to lines also
to install them)
cp vconfig /sbin
cp vconfig.8 /usr/share/man/man8/ (check if the other pages exist there)

The January 2011 issue of Linux Journal has an article on VLANs. The pdf is available now on their site. They did reference the documentation they found very useful in preparing the article.

Using distribution from Freescale for imx28 embedded target.

Kernel:
The i.MX Linux port is based on the standard Linux kernel. The kernel supports most of the features
available in many modern embedded OSs such as:
• Process and thread management
• Memory management (memory mapping, allocation/deallocation, MMU, and L1/L2 cache
control)
• Resource management (interrupts)
• Power management
• File systems (VFS, cramfs, ext2, ramfs, NFS, devfs, JFFS2, FAT, UBIFS)
• Linux Device Driver model
• Standardized APIs
• Networking stacks
ARM Linux Kernel customization to support each platform includes a custom kernel configuration and
MSL implementation.

Kernel Configuration:
For this BSP release, kernel configuration is performed through the Linux Target Image Builder (LTIB).
See the LTIB documentation for details. The configuration settings available on some platforms that are
different from the standard features are as follows:
• Embedded mode
• Module loading/unloading
• ARM9
• Supported file formats: ELF binaries, a.out, and ECOFF
• Block devices: Loopback, Ramdisk
• i.MX internal UART
• File systems: ext2, dev, proc, sysfs, cramfs, ramfs, JFFS2, FAT, pramfs
• Frame buffer
• Kernel debugging
• Automatic kernel module loading
• Power management
• Memory Technology Device (MTD) support
• USB Host/device multiplexing
• Unsorted Block Images (UBI) support
• Flash Translation Layer (FTL)
• CPU frequency scaling

For an embedded system you will have to use a cross compiler, but I don't expect this
to be very different that building other software for this platform.

you the source I mentioned before. It is not the original since that seems to exist no longer.
But I just tried and building vconfig on my machine from vconfig.c seems to work since I created a vlan with it.

gcc -o vconfig vconfig.c

So I think you can try to use you crosscompilation toolchain in a similar way to create the program
vconfig from this single c file.

Good luck