How can I transliterate a name in modern Russian characters to Slavonic?

Question

In an earlier question, I was misusing Google translate to try to get the spelling of a word, and I was pointed to http://translit.cc which would directly furnish spelling instead of trying to guess a preimage in English that would translate in Russian to Владыка.

Now I am wondering about transliteration from modern Russian to Church Slavonic, or if that's not available transliteration from modern English to Slavonic. The LMGTFY-grade answer I'd anticipate is to simply change like letters for like, as a transliteration between alphabets rather than a transliteration between completely separate languages. However, I'd like to avoid beginner's mistakes.

Is there a tool comparable to http://translit.cc, or should I just replace modern letters with ancient precursors and trust the naive approach?

--Clarification--

In the hopes of allowing this question to be reopened, I am adding what I put as a comment:

In my experience, English speakers who do not know Russian refer to the language of traditional Russian worship as "Slavonic" / "Old Slavonic" / "Church Slavonic." Native Russian speakers invariably, in my experience, say "Russian." I've read the Bible three times through in modern Russian and I'm chewing my way through the Slavonic, and the language is identifiably Russian. The linguistic distance between the Slavonic Bible on the one hand and a modern Russian translation on the other is about twice the distance between the KJV and the NIV, and the KJV is universally called English.

I know several Russian Orthodox, and all of them to my knowledge would place a question about old and new forms of Russian alphabet under the heading of the Russian language.

For further evidence, you might see a Russian video of the tale of Peter and Fevronia. After an initial animation showing an acronym in modern Russian letters, all the Russian that appears on the screen (the title of the video, a banner, people's names, etc.) are deliberately written in the Slavonic alphabet. The language of the video is modern Russian (plus English subtitles), but in Russian and in general there are times where it makes sense to Russians to write Russian content in the Slavonic alphabet.

Answer 1

Church Slavonic is a separate language that uses a superset of Russian alphabet. Hence transliteration from Russian to Church Slavonic will be the exact copy of the original Russian message, since every letter in the Russian alphabet is the same in Church Slavonic alphabet.

If you simply need the effect of using a different font, as they did in the cartoon about Peter and Fevronia, then you can use one of the publicly available fonts. You can look at fonts listed here: Church Slavonic Fonts I, personally, like the first one, at the top of the page (Irmologion).

If you need to change spelling of Russian words to make them look "older". Then you can either use pre-reform spelling converter as discussed here: What kind of Russian orthography is this?, or translate it into Church Slavonic.

However, if you really want to write text in Church Slavonic language. Then you need to learn that language: dictionary, grammar, etc. Church Slavonic can be written either using one of the fonts above, or using Roman Cyrillic Std font. Roman Cyrillic Std supports many of the additional letters that are needed to work with older texts.