Well Trace, I was hoppin that one of the master bait makers would help ya a bit...guess they're too busy tryin to get Boggy rouled up :? I'll try to get you started...remember this others have a bunch more experience at this.
You will be needing a base of some sort. Many start with tainted meat. This goes for bait or lures. If you just lightly taint the meat and stop there you will have bait. If you add varies musks, castors, kickers etc you will make a lure. Aging is up to you and will require you to make grub stakes and test circles to evaluate your product.
I guess since gophers are biger they'd be better / easier to work with than mice. Get yourself a bucket full and keep the flys from blowing them...this is going to be much more difficult in warm weather but it is important. Knock the guts out of the gophers (if you can find the Gall BLadders without much problems you might same these (freeze) for lateer use in specific lures. Some how you need to chop the gophers into small chunks or grind them with a meat grinder that your mom etc doesn't use for food (the gophers won't ruin the grinder but you can bet that your mom will ruin your day if she catches you).
Put your choppings / grindings in a container with a tight fitting lid. From this lid you need to attach a tubeone end through the lild but not in the meat the other end in a container of water. This is a vent / trap the fermentation gases can escape and the flies can't get in. I'd do thiss away from people and in as cool a place as you can find...this time of year in your country things will go fast...fast isn't good for control. In a week or so the meat will be tainted you will be able to smell the trimethly amines.
When you get a taint that you like add sodium benzoate to stop the microbial growth and preserve the concotion. Now is a good time to add things try beaver castor and / tonquin and / or muskart musk-glands and / or asafoedia. How much you ask? which combination is best you ask? Them are well gaurded secrets! Mel Hershberger published some and I can get them for you once you are getting close to needing them.
You can also get a mess of carp, gut them, grind them and sun dry them (don't let the flies get on the meat). Ole RdFx claims that a spoon full of this down a hole is good bait. I'd even try blending the dried fish with some lightly tainted gopher plus some castor.
If you make 3/5's of a 5 gal bucket to start, you can then take a gallon out maybe three times at different stages of taint...just after you start getting the smell...two weeks or so later...and at the end of summer. The last will probably only be good for lures...I think.
Now you can split each gal into quarts and try four combinations of musks etc. Start off with small amount of musks test them ...add more of one or the other test them and see what works. Hershbergers formulas worked for him and should be a good starting place.
Hope this gets you started
One last thing, asking a lure maker for his formula is like asking him for the combonation to his safe.