First off, why were you removing that cover at all ? was it another problem ?
To fix the leak, you are probably going to have to get that cover off, somehow.
Now "stripped" ? do you mean the THREADS are stripped ?
Or did you run into those damn be-cursed no-account bastard Hex-head bolts ?
So, is the threads stripped, or just the top of the bolt ?
My reccommendation is to get that cover off even if you have to pay someone else to do it, then take one of those evil-damn-hex-heads to the local hardware store and have them give you FLAT HEAD machine bolts with the same thread and depth, so you don't have that problem any more.
Also it's likely that the paper gasket in there might be torn, or worn...so why not replace it while yer at it.
If the threads are stripped too, you'll have to re-tap and put a slightly larger bolt in there, is all.
And once you put it back together, fill it up with 220cc's of either Dexron III ATF (Targa) or 10w30 (Bullet), and there you go.
It really does help if I get a comprehensive description, and if you wanna guarantee I at least look at the thread, mention Tomos in the subject line.
Best of luck,