面接の練習をしたいのですがって英語でなんて言うの？

You may have some questions prepared that will be asked for an upcoming interview, or your teacher may have some good suggestions of what to practice.
You may want to specify what you need help with for your interview, whether that's figuring out what questions will be asked, common courtesies or helping you respond confidently.

To assist means to help. Therefore you would like their help to practice for the English interview.

A 'mock' interview is a practice interview.

To run through something - to practice something; to rehearse:
"The director wants us to run through the first act this morning." If you run someone through something, you practice it or talk about it so the person will know it better:
"A technician ran me through the data recovery process."
To go over something - to examine or look at something in a careful or detailed way:
" I've gone over the problem several times, but I can't think of a solution."

There are several ways to ask for help practicing for an interview, depending on how you would like to prepare. If you want to discuss or practice specific skills, you could ask "Could you help me practice my interview skills? This might focus on things like answering questions in complete sentences, or speaking clearly without saying um or like.
If you would rather practice by pretending you are actually being interviewed, then you might want to ask "Could we role-play for an interview?" This will make it clear that you would like the person to act as though they are your potential employer and treat you as though you are currently at the interview.
Finally, if you would like to combine these types of preparation methods, then you could say "Could you help me prepare for an interview?" Then you can begin by discussing skills or concerns you would like to focus on, and then perhaps finish with a practice role-play session.

If you would like to ask someone for help to practice an English interview with you, you can say something like "Can you help me practice for my English interview please?" or " Would you help me practice for an English interview I have coming up please?". These are both polite ways to express this.

You are asking for someone's help or assistance so your sentence should begin with please. That way you are far more likely to get a positive response.

All mean the same thing, all work, and you will certainly be understood.

You can ask for help to practice or prepare, which can be used interchangeably for the interview. Usually, people want to practice for interviews so they are proficient and look well versed, so you want to practice and seem prepared. Also, one wants to ask for help in a pleasant manner, so always use please and thank you.