Tera Term is really text based and will give you fits if you try to operate at a lower level for hex data (but it is possible). It seems to be intended and best suited for sending/receiving printable ascii characters.
For example, if you open Tera Term and connect to your desired serial/COM port then the ASCII/hex value of each key you type on the keyboard will be sent out serially to the device connected on that serial port and anything it sends back to you will show up in your terminal window. So, if you type the following keys: "T" "h" "i" "s" " " "i" "s" " " "a" " " "c" "o" "m" "m" "a" "n" "d", it will actually transmit the hex value corresponding to each ASCII character as you type (which from an ASCII lookup table you will find is 0x54(T), 0x68(h), 0x69(i), 0x73(s), 0x20( ), 0x69(i), 0x73(s), 0x20( ), 0x61(a), 0x20( ), 0x63(c), 0x6F(o), 0x6D(m), 0x6D(m), 0x61(a), 0x6E(n), and 0x64(d)). This is fine as long as the hex values you want to use are between 0x20 and 0x7F and generally correspond to the keys on your keyboard (0x00 to 0x1F are the command characters that don't print to the screen). You will have to do a lot of translating from the keyboard key (ascii character to the equivalent hex value), but it can be done.
If the commands you need to send to your device need to use the hex values from 0x00 to 0x1F or 0x80 to 0xFF, then you will most likely need to bite the bullet and learn how to write simple macros that will transmit the commands you want. They don't have to be big and scary and can be quite simple actually. For example, you could write a simple macro for each command you want to send and then from Tera Term you would run the macro for the command you want to send (select Control-->Macro, and it will open up a window that lets you browse to and select the macro you want to run in Tera Term). If you are going to be getting responses back from the serial device, then you will probably want to put Tera Term in debug mode so that it displays each received byte as a hex number separated by spaces (so instead of seeing "COM1=" coming from the device you would see the raw hex data 43 4F 4D 31 3D). Trevor already gave you some good samples. The macros are just simple text files that give commands to Tera Term (such as to transmit data). At its most simple your macro could be a text file saved as command1.ttl with the following lines:
setdebug 2 ; this sets the Tera Term window to display all received data as hex bytes separated by spaces
If you use the TTLEditor to do this it would look something like: