Just a quick note here because I couldn't find Windows 10 instructions on here.
I have a Mini-VCI J2534 cable which worked happily with my Techstream 10 install on 64 bit Windows 7, after some faffing. Anyway, had to give that laptop back last month when I left the job I'd acquired it from.
Windows 10 has a few more challenges. You need at least Techstream 12 (you could hack about with the registry to get Techstream 10 to work, nit don't waste your time). And you need to get Windows 10 to load 64 bit drivers for the cable. Windows 10 really doesn't want to let you load old, unsigned drivers. You can do it, but it'll make it hard for you.
So a bit of googling and a bit of trial and error and these steps seem to work.
http://blog.obdii365.com/2017/12/03/toyota-techstream-12-30-017-download-and-install/
Follow the steps under : Techstream install Windows 10.
Step 2. You want to run this from the cmd prompt as the admin user. (type 'cmd' in the Type here to search box in the bottom left of your screen)
Step 4. Copy all of the contents of the file in the link to notepad (dont copy and paste from the steps, there are extra spaces in there), and save as filename.reg
You then import that file using Regisitry Editor (type 'registry' in the Type here to search box). Select the import option from the File menu (top of the screen).
Some instructions suggest running a firmware update tool to confirm the cable install has worked; but the tool doesn't work in Windows 10. Don't waste your time like I did!
Step 7. You can get Techstream 12 from here : https://mega.nz/#!9NBllR4R!v1hY8XHTcT-RBJfQypQ5zIDLypBDJ12LHy6zDqdNOFA I did virus check this, but . at your own risk. To extract this file you need to copy it to the desktop then open it with a zip program, such as Winzip. You may need to download that from somewhere.
Check the instructions.txt in the unzipped files. Theres a few simple steps to complete the install.
All working fine now. Just got to figure out how to get my copy of the workshop manual to fire up now. It doesn't seem to like new versions of Internet Explorer.

This is TOYOTA TIS Techstream 10.30.029 update and installation guide.
Toyota TIS Techstream 10.30.029 software download
Operating system requirement:
XP or “XP Mode” in Windows 7 (except win 7 home)
A part of users use VMware and XP Professional.
Languages available:
Chinese, English,French, German, Italy, Japanese, Spanish
Techstream tools:
Step 1- install Toyota Teachstream
Open “Toyota Techstream 10.30.029.exe”
Select a steup language to go on
Click Next
Accept the agreement to go on
Customer information: click Next
Click Install to begin installation of Techstream 10.30.029
Finish installing Techstream
Step 2- install MVCI driver for TIS
Open “MVCI Driver for Toyota”
Click Next
Click Install to begin installation of the MVCI driver for TIS
Finish installing MVCI driver for TIS
Step 3- paste and replace Main Menu
Copy “MainMenu” application
Open Techstream Properties
Click Find Target
Paste “MainMenu” application in C:/program files/toyota diagnostics/techstream/bin, confirm file replace
Close bin folder and Techstream Properties
Connect the device (new Mini VCI, mini VCI for Toyota 22 pin, MVCI,Mangoose techstream, VXDIAG NANO) to the vehicle and then install the driver
Open “Techstream” on Desktop
Click No
Select Setup->Techstream configuration
Select an area (here: Europe), click Next
Select a language (here: English), click Next
Techstream configuration, click OK
open Desktop folder “Toyota Techstream”->notepad “serie”
Copy the key
Click Connect to vehicle in Techstream interface
Paste as the New Key when register Techstream software, click OK
Finish Option (here: VIOS, China & 1205-), click Next
Select Engine and ETC to continue
Trouble codes display
Select Data list on the left menu
(Lost communication with vehicle: click Retry)
Click Close->Main Menu->Log out (Techstream)