First, you’d need to install Debian on your server. For DelimiterVPS, go to https://clients.delimitervps.com/clientarea.php, and login to your account.
Choose the Reinstall server option.
Under ‘Installation Profile’, choose ‘Debian Wheezy’.
Choose a good enough root password. From personal experience, I’d avoid special characters in my root password. I had setup a very complex password once, and found that it was not accepted by the ssh login shell. It’s likely that WHMCS does not escape special characters very well.
Choose ‘Provision Server (Warning)’.

At this point, go back to the email you received from DelimiterVPS, and read the part about KVM/ILO Configuration. You can login to ILO and watch the installation progress. Once installation is done, Proxmox is supposed to be up and running at https://yourip::8006. However we need a couple of steps and a reboot before we can use it.

Run the following:

cat << EOF > /etc/apt/sources.list.d/openvz-rhel6.list
deb http://download.openvz.org/debian wheezy main
EOF
wget http://ftp.openvz.org/debian/archive.key
apt-key add archive.key
apt-get update

Install OpenVZ kernel:

apt-get install linux-image-openvz-amd64

First, you have to remove the default Linux kernel, and set the OpenVZ kernel to start at boot.
Run the following from the shell:

apt-get remove linux-image-amd64 linux-image-3.2.0-4-amd64 linux-base
update-grub

You’ll notice that openvz based kernels have now been added to grub (the bootloader).

Enable IP forwarding and other rules are setup:
Edit the file /etc/sysctl.conf, and uncomment/add (Remove the # at the beginning) the following lines:

# On Hardware Node we generally need
# packet forwarding enabled and proxy arp disabled
net.ipv4.ip_forward = 1
net.ipv6.conf.default.forwarding = 1
net.ipv6.conf.all.forwarding = 1
net.ipv4.conf.default.proxy_arp = 0

# Enables source route verification
net.ipv4.conf.all.rp_filter = 1

# Enables the magic-sysrq key
kernel.sysrq = 1

# We do not want all our interfaces to send redirects
net.ipv4.conf.default.send_redirects = 1
net.ipv4.conf.all.send_redirects = 0

run the following:

sysctl -p
apt-get install vzctl vzquota ploop vzstats

Now, restart the server. 

reboot

Run the following:

wget -O - http://ovz-web-panel.googlecode.com/svn/installer/ai.sh | sh

After some time the installation may stop with the following message:
Fatal error: Panel requires Ruby 1.8 (Ruby 1.9 is not supported).

Run:

update-alternatives --config ruby
# update-alternatives --config ruby
There are 2 choices for the alternative ruby (providing /usr/bin/ruby).

  Selection    Path                Priority   Status
------------------------------------------------------------
* 0            /usr/bin/ruby1.9.1   51        auto mode
  1            /usr/bin/ruby1.8     50        manual mode
  2            /usr/bin/ruby1.9.1   51        manual mode

Press enter to keep the current choice[*], or type selection number: 1

Now rerun the installation:

wget -O - http://ovz-web-panel.googlecode.com/svn/installer/ai.sh | sh

At the end, you will get the message:

Panel should be available at:
http://x.droidzone.in:3000
Default credentials: admin/admin

Now login, and change the default password.

You can now install OpenVZ templates(Physical servers>Localhost>OS Templates>Install new OS Template).
Assign ips to the pool (Ip Addresses>Create new IP pool). Add the IPs assigned to you. You may need to buy more from your provider.

To create a VPS:
Localhost>Virtual servers list>Create virtual server

Creating a custom template.
Provision a VPS using a default template.
Login to the VPS, setup everything including resolvconf, tzdata, locales, dialog, .bashrc etc.

vzctl stop 1
vzctl set 1 --ipdel all --save
cd /var/lib/vz/private/1
tar --numeric-owner -czf /var/lib/vz/template/cache/debian-7.0-x86_64-minimal-custom.tar.gz .

Change default port and enable SSL on Openvz web panel:
Change the following in /etc/owp.conf:

# web server port
PORT=3000

to

PORT=2096

and

# SSL support, on - enable, off - disable
SSL=off

to

SSL=on

Restart the service. Now it is accessible at https://yourdomain.com:2096

I chose 2096 because it is one of the ports that Cloudflare supports and thus you get a free SSL support with Cloudflare.

Create a symlink to /vz because most of the vz tools expects the OpenVZ folders to reside there. This step is not necessary, but can eliminate further problems when other vz related components are installed.

ln -s /var/lib/vz /vz

You also probably need to change:

#NEIGHBOUR_DEVS="detect"

to

NEIGHBOUR_DEVS="all"

at /etc/vz/vz.conf

and do a 

service vz restart

For Reference, my network config on node is as below:

# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
allow-hotplug eth0
iface eth0 inet static
        address 157.266.186.60
        netmask 255.255.255.192
        network 157.266.186.0
        broadcast 157.266.186.63
        gateway 157.266.186.62
        # dns-* options are implemented by the resolvconf package, if installed
        dns-nameservers 8.8.8.8
        dns-search droidzone.in

And my two addon ips are: 

157.266.187.162/32
157.266.187.163/32

Obviously the ips have been scrambled.