How can I install Android (any version, it dosen’t matter which) on my Samsung Rex 90?
You can't. It uses a different architecture and chipsets, and has very little memory. There's simply no way to do this.
well i think Samsung Rex 90 phones are budget phones with Java software, in order to install android hardware requirements are necessary?
Samsung Rex 90 XMM 2230 , 312Mhz 32bits Single-Core
The main hardware platform for Android is the 32-bit ARMv7 architecture. There is support for x86 from the Android-x86 project, and Google TV uses a special x86 version of Android. In 2012, Intel processors began to appear on more mainstream Android platforms, such as phones. In 2013, Freescale announced support for Android on its i.MX processor, specifically the i.MX5X and i.MX6X series.