Is it possible for homeschooling teens to do dual enrollment courses? In general, yes. Though I've heard rumbles that some states still have legislation on the books that makes it difficult for a homeschooled student to enter college. Texas passed specific legislation that states colleges can't treat homeschooled students any differently from other students when it comes to admissions, but there are still laws regarding minimum age for enrollment that many colleges will use to try and keep homeschooled students out of dual-enrollment programs.
As an independent education consultant, I advise homeschooling families to prepare themselves for argument. Document the courses/levels the student has already completed and prepare a statement indicating how the student will benefit from dual-enrollment and exactly what sort of credit will be provided to the student. Then pick up the phone and contact the admissions counselor at your local public community college or university and/or private college (sometimes private schools are easier to deal with) and talk with them a bout your student's specific situation.
Regarding courses/content/curriculum for high-school students, I've seen TONS of curriculum available on the web for grades 8 through 12. In some instances, there are even online courses made available through a local university. For instance, Texas Tech University actually hosts an accredited online program (http://www.depts.ttu.edu/oes/
) through its Outreach and Extended Studies Department and so does the University of Texas at Austin (http://www.utexas.edu/cee/dec/uths/index.shtml
If you would like more information on planning for your child's college admissions, contact an admissions counselor at a university your child is interested in, contact an independent education consultant in your area, or visit my business site http://www.hillcountryecs.com.