Here is a brief passage from the methods of study which also used a hypercholesterolemic mouse model. I would suggest doing a more extensive literature search (through resources such as pubmed, google scholar) before planning any sort of treatment routine. I also must strongly urge that you work closely with someone who has extensive experience with animal research - there are many safety, ethical, and legal concerns to be aware of before getting started.

Here is an example paper to get your search started:
M.P. Taranto, M. Medici, G. Perdigon, A.P. Ruiz Holgado, G.F. Valdez, Evidence for Hypocholesterolemic Effect of Lactobacillus reuteri in Hypercholesterolemic Mice, Journal of Dairy Science, Volume 81, Issue 9, September 1998, Pages 2336-2340, ISSN 0022-0302, 10.3168/jds.S0022-0302(98)70123-7.

Mice and the Hypercholesterolemic Animal Model Swiss Albino mice weighing 25 g were obtained from the randomly numbered closed colony kept at CERELA. The mice were split into two groups. Each experimental group consisted of 10 mice housed in- dividually and maintained on a cycle of 12 h of light and 12 h of dark. As a preliminary treatment to produce hyper- cholesterolemia, the treated mice were fed a diet based on 10% ( w t / v o l ) sterile NDM supplemented with 10% cream for 7 or 15 consecutive d. The control and the HC groups received a solid conventional diet (rodent chow: 32% protein, 5% fat, 2% fiber, and 60% nitrogen- free extract). The total fat content of the diet was 17.6% for HC group and 6.7% for the control group. After 1 and 2 wk of feeding, blood samples of 10 mice per group were drawn from the retroorbital venous plexus for determination of serum total cholesterol, HDL cholesterol, LDL cholesterol, and serum triglycerides. The cholesterol and triglycerides concentrations were determined enzymatically using an enzymatic reagent kit (Sigma Chemical Co., St. Louis, MO).

I don't think you're allowed to do that type of research. Researchers need approval from their university and the government to do animal research of that type. Animals have rights.

I used to do research at UC Berkeley on cholesterol-fed guinea pigs. We used guinea pigs instead of mice or rats, because guinea pigs get high blood cholesterol from dietary cholesterol much more easily than rats. I'm guessing mice respond about the same as rats.

So I hope you can find a new research project, and I congratulate you on planning to do a research project.

There's also Google Scholar - scholar.google.com - where you can find scientific articles. You might want to search for something like : mice blood diet cholesterol.

Here's the first article from that search - you can click on : [pdf] from NIH.gov to see the whole article. But don't try this at home!! ;-] Massive xanthomatosis and atherosclerosis in cholesterol-fed low density lipoprotein receptor- negative mice.

[PDF] from nih.gov S Ishibashi, JL Goldstein, MS Brown... - Journal of Clinical ..., 1994 - ncbi.nlm.nih.gov ... Mice with the indicated genotype (n = 6; three males and three females) were fed either a normal chow diet (o) or a 1.25% cholesterol (*) diet for 6 mo. Blood was obtained from nonfasted animals, the d < 1.215 g/ml lipoprotein fraction of pooled plasma from each group was ... Cited by 442 - Related articles - BL Direct - All 14 versions.

As with all animal experiments, you should talk to your teacher about it. Is there another way you can complete your project without having to use mice? Can you do a study surveying your friends and family about their diet and correlate it with whatever you are trying to study? It is likely whatever you are interested in studying, can be approached without the use of animals.

If you must use mice, you do not want to cause the animals to suffer in your experiments. You and your teacher should come up with a plan for your mice. How many mice will you have? Where will you put them? What will happen if the mice get sick? This also means that you should have an idea of what you are going to do with the mice after the experiment. They should be healthy enough to go to good homes. Scientists that use animals in their experiments are subject to very harsh review before they use animals in their experiments and need to answer questions such as these to even be able to proceed. You should think about your experiment carefully before using mice.

One way to induce hypercholesterolemia is to supplement the normal rodent food with 10% cream for 7-15 consecutive days (see Materials & Methods for Taranto 1998). You'll want to look at the rodent food to see what it's nutritional content is as well. Follow the general feeding procedures for the mouse as recommended by the label on the rodent food.

Another study described the normal feed as being 22.5% wheat flour, 60% roasted Bengal-gram flour, 5% skimmed milk powder, 4% casein, 4% refined groundnut oil, 4% salt mixture, and 0.5% vitamin mixture (as recommended for mice). To increase cholesterol, they added 2% cholesterol and 1.5% sodium cholate (see Materials & Methods for Dutta 2009).