How can the ~たい form of a verb be modified for past/present or positive/negative use?

Question

Background

I'm aware that the ~たい form of a verb indicates wanting to do something, though - until recently - I hadn't thought about how I could say that I didn't want to do something.

A quick internet search lead me to this page of Tae Kim's guide, with the following example:

3. 怖い映画は、見たくないよ。
   (I) don't want to watch (a) scary movie.

I also came across another site, which mentions past-tense variants for both the positive (~たい) and negative (~くない) forms:

Any Japanese -tai form verb conjugates just like an -i adjective does, so here is an example with miru (to see):

Present Tense | Present Tense Neg. | Past Tense | Past Tense Neg.

mitai         | mitakunai          | mitakatta  | mitakunakatta

You can see those conjugations as "want to," "don't want to," "wanted to," and "didn't want to" in English.

However, I was confused about how, say, 飲む would be made negative - some of the guides I came across were rather vague, and seemed to indicate that I should replace the ~ む with ~くない (or perhaps just the ~u, with ~akunai), giving either 飲くない or 飲まくない. Neither of these seemed correct; I believe that it should actually be 飲んだくない.

The answer(?)

My understanding is that I can derive the past/present and positive/negative ~たい variants of a verb as follows:

• Present (Positive): The formal, positive-present conjugation with ~たい instead of ~ます.
• Present (Negative): The plain, positive-past conjugation with ~くない on the end.
• Past: As above, but with ~かった in place of ~い.

Here are some examples, based on the above:

• 飲む
  • 飲みます → 飲み(たい) → 飲みた(かった)
  • 飲んだ → 飲んだ(くない) → 飲んだくな(かった)
• 黙る
  • 黙ります → 黙り(たい) → 黙りた(かった)
  • 黙った → 黙った(くない) → 黙ったくな(かった)
• 話す
  • 話します → 話し(たい) → 話した(かった)
  • 話した → 話した(くない) → 話したくな(かった)
• 食べる
  • 食べます → 食べ(たい) → 食べた(かった)
  • 食べた → 食べた(くない) → 食べたくな(かった)
• する
  • します → し(たい) → した(かった)
  • した → した(くない) → したくな(かった)
• 来る
  • 来ます → 来(たい) → 来た(かった)
  • 来た → 来た(くない) → 来たくな(かった)

tl;dr

Do the "rules" above correctly describe how verbs are modified to indicate (not) wanting to do something, in both the past and present tense?

Also: Is adding です afterwards the correct way to make a variant more polite, regardless of whether it is past/present or positive/negative? For example, are 飲みたいです / 飲んだくないです / 飲みたかったです / 飲んだくなかったです all acceptable?

Answer 1

【たい】follows 【連用形】 (the continuative form, masu-form, i.e 飲み, 食べ,　歩き)　so you can't attach it to 【過去形】 (past tense, but other stuff as well). Instead you conjugate 【たい】 to the correct tense to indicate you wanted to do something in that time period.

Example of positive ~たい:

飲みたい (I want to drink)

飲みたかった　(I wanted to drink)

Example of negative ~たい:

飲みたくない (I don't want to drink)

飲みたくなかった (I didn't want to drink)

You are spot on about 【です】, however. It's the polite version of 【だ】.