Drop your jaw slightly with relaxed lips. Touch the tongue tip behind the bottom front teeth and arch the top-front toward the roof.

Americans pronounce intellectual as ihn-tuh-LEHK-choo-uhl (/ˌɪntəˈlɛktʃuəl/). In "intellectual", the "t" right after N is dropped — the tongue skips the T stop and moves directly from the N position to the next sound. This is called the Silent T after N, a small move that separates 'classroom' from 'native'. It comes out as IHN·tuh·LEHK·choo·uhl. Stress falls on the third syllable — keep everything else short and quick. You'll hear it in sentences like "The intellectual property rights are protected by copyright law".
Record yourself saying "intellectual" and play it back. The mic stays on your device — nothing's uploaded.
5 syllables, 11 sounds. Tap a syllable to jump to its row, then explore each sound's mouth shape and how it's made.
The schwa before L disappears — L becomes the vowel of the syllable. Go straight from the previous consonant to a Dark L.

Drop your jaw moderately. Touch the tongue tip behind the bottom front teeth and lift the mid-front part slightly toward the roof.

Raise the back of your tongue to touch the soft palate (velum). Stop the air, then release.

The textbook way isn't wrong — it's just not how anyone actually says it.
In "intellectual", the "t" right after N is dropped — the tongue skips the T stop and moves directly from the N position to the next sound. /t/ is completely silent — the tongue skips the T stop and moves directly from the N position to the next sound.
The L in "intellectual" is a dark L — the back of the tongue rises toward the soft palate, adding a small "uh" quality before the L. Dark L adds a small schwa-like "uh" before the L. The back of the tongue lifts toward the soft palate.
In "intellectual", the "k" is not released — the articulators get into position but hold without the burst of air. Air stops but there's no release burst — the articulators hold position.
In "intellectual", the short unstressed vowel before "l" disappears — the schwa is absorbed and the "l" becomes the syllable nucleus on its own. Schwa is absorbed — consonant becomes the syllable nucleus.