How do I properly wear a pair of english spurs?

Hokay, here is the deal, I just bought these spurs:

http://www.smartpakequine.com/m-toulouse-soft-touc...

I ride in paddock boots with half chaps, and my boots don't have a spur rest. Where is the best place to have the spur placed, what is the best way to keep them from slipping, and is there anything else I should know?

More unnecessary info on why I need spurs/help (read or don't, I don't really care):

I have been riding english for about 10 years now (I am 21), and I haven't worn spurs in about 7 years. I started out riding hunter/jumper, and almost every rider wore spurs - if you didn't have them you were a newbie and everyone looked down on you (stupid, I know). After a bad accident (four surgeries bad) three years into my riding career, I switched barns and disciplines to dressage, and learned a bunch of natural horsemanship. While riding does NOT come naturally to me (I have to work really hard to do it right), I found I am awesome at teaching naughty horses ground manners. The combination of those two disciplines taught me that I was using a spur for all the wrong reasons in all the wrong ways. Since then I have ridden mostly dressage and competitive trail, dabbling back into hunter jumper in the past two years, only because I think it is important to know how to safely ride a jumping horse, especially if you trail ride like I do (cross country, not many trails). Durring that whole time, I avoided spurs because I was afraid of misusing them again, and the level of riding I was doing didn't require them for subtlety of communication.

Fast forward to 8 months ago: my rather impressive collection of birth defects in my spine start acting up. I am essentially bed/wheelchair ridden for 6 months - I lose all my riding muscles. Now go to 2 months ago when I convince my doctors to let me start riding again (it is actually really good for my back), but only if it is through a hippotherapy program with a licensed physical therapists and a therapy horse. And now we are at today. I am up to being in the saddle for 30 minutes at a time, and my physical therapy sessions are now about 50% physical therapy, and 50% retraining my body how to actually ride. I basically have all the muscle memory, but none of the muscle.

Now about the horse I am riding: beautiful dappled palomino quarter horse, trained from the get go to be a therapy horse and not a riding horse. She is perfectly happy to have both physically and mentally handicapped people on her back, and she will walk out beautifully, ignoring essentially everything going on on her back (screaming, hitting, flopping, kicking, etc). If you put a competent rider on her back, with a gentle snaffle in her mouth, she knows how to turn, but not to bend, she knows how to stop, but not collect, and if she ever decides to listen to your leg, all cues mean go forward. I have fallen desperately in love with this little mare, and I have gotten permission to start trying to get a little bit of training into her. I will be doing ground/ wheelchair work with her (what I am really good at) and half of my riding sessions will be devoted to training/real riding. She is the perfect horse for me to start all over with.

Two problems: she is dead to the leg (since she was trained that way), and because of the combination of nerve damage and muscle atrophy, I don't have the leg strength to support her, and I may never redevelop it. My hands and arms have enough nerve damage to them that I can hold reins OR a dressage whip, but not both. However, because of the muscle memory thing, I have both quiet hands and legs (I am SO glad I learned that before I had this flare up, I would never be able to learn it now). Obvious solution: spurs.

I bought myself some really gentle spurs, dusted off my old spur straps and battled them onto my boots. My boots don't have spur rests, because when I bought them 3 years ago, I never expected to need them. I know you can use spurs on boots without spur rests, and you are supposed to put them at the seam between the heal and ankle, but I really don't see them staying there, no matter how tight I make the spur straps. My other boots are my tall boots - which I don't want to wear because they block too much of the remaining sensitivity in my legs, and my trail boots which are ariat terrain boots and do have a spur rest but not enough ankle support for arena work.

Anyways, I am going to ride in my new spurs for the first time this coming Tuesday, and I foresee a few problems: Will they slip, will I be able to apply them correctly, and even though I know that I won't hurt her (my leg is still and these are super gentle), how do I keep my confidence up while using them? I can see myself riding with my leg pulled off her side in order to make myself sure that I am not poking her, which is not helpful to either of us.

Thanks in advance,

Andi