Use the latest version of Tiny Core. New versions have improvements and additional features.
For installation guides, see the Index.
The easiest way to install an earlier version is using the multicore iso, with tinycore.gz and bzImage from an earlier version.
To do this, follow one of the installation guides in the Index, but have tinycore.gz and bzImage from an earlier version available, and select tinycore.gz from the earlier version.
Another option is to install the latest version, then after installation, replace tinycore.gz and bzImage with those from an earlier version.
Version 3.6 may also be installed using one of these methods.
Version 3.5 and earlier may be installed on a USB drive using USB Install, which may be found in the Control Panel.
Any version may be installed on a hard drive using one of these methods.
However, the installation methods listed in the Index are easier.