One reason it can be hard to find HS'ing info in Texas is that Texas is the EASIEST state to homeschool in in the entire country. Here's what the state government has to say about HS'ing in Tx:
"In Texas, we view home schooling as something to be respected and protected - respected for the energy and commitment of parents; protected from the interference of government. Texas does not index or monitor home school programs."
There are absolutely *no* requirements/oversight in Tx... and Trust me... on nationwide Homeschooling boards those of us outside Tx DROOL. I live in a fairly "easy" state, but Texas is the *best*. Especially for those with gifted kids, LD kids, and psych issue kids. (Having an ADHD-c 8yo, I've got all 3 in my one amazing kiddo :).
I'm obviously biased, already being a HS'er, but I believe your daughter's idea to homeschool to be brilliant. Not only will it give your granddaughter time to get her meds straightened out (typically takes 12-18 mo to find the correct meds, combos, and doses) without impacting her academics, but HS'ing is a *huge* leg up for college. HS'ers are accepted at 6:1 against public/private schooled kids in the ivy leagues, and our kids have a leg up on state schools as well (in large part because our kids get to present portfolios of their work instead of trying to cram every bit of *sparkle* into a short essay), although the Ivies actually recruit HS'ers. ALSO in part is that most states offer "dual enrollment" programs. So highschool students can take classes at the community college (college level) for FREE. They can just pad their HS curriculum (for example, a literary kid could take tons of classes in the humanities / or lit dept... a math kid could delve into college level maths... artsy kid into college level art, etc.), or use CC credits *as* their highschool curriculum, or be ready to transfer into a state school with a 2 year degree by the time their peers are graduating highschool.
((Ahem... so as far as curriculum goes, *do* look up the dual enrollment options available in your state.))
But my gushing aside... here's some links to find much more help than I could provide:
Texas (support groups and laws)
http://homeschooling.gomilpitas.com/extras/Search.htm?cx=...
A yahoo group specifically for HS'ing special needs kids. (If you or your daughter doesn't already have a yahoo ID they're free to create. It takes about 24 hours for most groups to approve your entry into them -they're moderated, the moderators make you fill out a brief form to prevent spamming)
http://groups.yahoo.com/group/Homeschool_SpecialNeedsKidz...
A very active secular homeschool yahoo group ((one you're in yahoo group just search ____________ homeschool. Texas Homeschool, Dallas Homeschool, Teen Homeschool, Bipolar Homeschool, Christian Homeschool, Secular Homeschool, etc. Some boards are more active than others.))
http://groups.yahoo.com/group/secular_homeschoolers/
My absolute FAVORITE general homeschooling website. Tons of information on various styles, philosophies, curriculum, etc... written by people who actually practice those styles/ philosophies or use the curriculum, instead of the views on 1 or a handful of people who are biased towards their own favorites.
http://www.homeschooldiner.com/
The BEST curriculum site out there (imho), amazing discounts (we got discovery science for $50 when Discovery.edu price if buying straight from them is $700). Lots and lots of trials / demos, all arranged by subject so it's easy to form your own opinion / let your child try them out ... instead of crossing your fingers and hoping based off of someone else's review.
http://www.homeschoolbuyersco-op.org/