Wiktionary:Lü transliteration

No policy has been established for the transliteration of Lü. The language is mainly written in two scripts, the New Tai Lue script and the Tai Tham script.

Wikipedia has basic descriptions of the two scripts at New Tai Lue alphabet on Wikipedia.Wikipedia and Tai Tham script on Wikipedia.Wikipedia . There are more extensive compound vowel tables in an article in the Northern Thai incubator Wikipedia, and the two writing systems are described in:

เตชะศิริวรรณ, อภิรดี (2003 May 2) “พัฒนาการของอักษรและอัขรวิธีในเอกสานไทลื้ [Development of Tai-Lue Scripts and Orthography]”, in khamkoo.com[1] (in Thai) (pdf)