The Mojikyo system includes two fonts (Mojikyo M202 and M203) which provide Tangut glyphs mapped to CJK code points. You can convert Tangut text using the Mojikyo font to Unicode Tangut using the online Mojikyo to Unicode Converter. Simply paste text into the top text box (which should be displayed using the Mojikyo font if installed on your system), then press one of the "Convert" buttons, and the converted Unicode text will be put in the bottom text box. The converted Unicode text may then be copied to the clipboard by pressing the "Copy" button.
The Tangut fonts M202 and M203 cover 6,000 Tangut characters for Mojikyo version 4.50 and earlier. Mojikyo version 4.60 (2014) and later cover an additional 77 Tangut characters in M203, and remap six existing M203 code points for new Tangut characters. There are also many glyph changes in the later version of the fonts. To convert from Mojikyo v. 4.50 and earlier, click on the "Convert (Old)" button, and to convert from Mojikyo v. 4.60 and later, click on the "Convert (New)" button.
There are 360 code points in both fonts (M202 and M203) that are mapped to different Tangut characters, so it is impossible to do a simple plain text conversion. For the 360 double-mapped code points (as well as for the 77 additional characters in the new version of the M203 font), the two Tangut characters in both fonts are put in braces, and you will have to manually choose which is the correct Tangut character in the context.