Tools and utilities is available on ESXi, – busybox executable

~ # /usr/lib/vmware/busybox/bin/busybox --list
[
[[
addgroup
adduser
ash
awk
basename
cat
chgrp
chmod
chown
chvt
cksum
clear
cp
crond
cut
date
dd
delgroup
deluser
diff
dirname
dnsdomainname
du
echo
egrep
eject
env
expr
false
fdisk
fgrep
find
getty
grep
groups
gunzip
gzip
halt
head
hexdump
hostname
inetd
init
kill
ln
logger
login
ls
lzop
lzopcat
md5sum
mkdir
mkfifo
mknod
mktemp
more
mv
nohup
nslookup
od
passwd
poweroff
printf
readlink
reboot
reset
resize
rm
rmdir
sed
seq
setsid
sh
sha1sum
sha256sum
sha512sum
sleep
sort
stat
stty
sum
sync
tail
tar
tee
test
time
timeout
touch
true
uname
uniq
unlzop
unzip
usleep
vi
watch
wc
wget
which
who
xargs
zcat

How to wget from a ISO source:

# cd /vmfs/volumes/datastore_name_here

Load 2012 into the data store

# wget cd http://care.dlservice.microsoft.com/dl/download/6/2/A/62A76ABB-9990-4EFC-A4FE-C7D698DAEB96/9600.17050.WINBLUE_REFRESH.140317-1640_X64FRE_SERVER_EVAL_EN-US-IR3_SSS_X64FREE_EN-US_DV9.ISO