Greetings
I have used a very similar system called supercal which comes as a complete kit in local model shops here in the UK.
It has sheets of a5 paper, *both transparent backed and white backed, and a spray coating in a can.
I have used it very sucessfully *with my other modelling hat on, that of model railways.
Theres a couple of rules involved though..
1) *You can't print white *( you can print a white raven for von rabens tripe by printing a red square on the white backed stock and leaving a hole raven shaped, but you need to match the red

*)
2) *you have to print the whole a5 sheet at once, no return feeds.
3) *when printed you have to let the ink dry thouroughly, and I mean about a week in a warm place, otherwise when you spray it with the overspray after a while the decals can still "spread" slightly under the spray and become fuzzy.
4) *the carrier is quite thick. needs lots of loving microsol to get it to bed down and is better if you can cut the transfer to fit a panel line or somesuch.
5) *its only as good as your artwork and your printer. *I use a HP deskjet 970CxI and Corel Graphics.
I don't believe it is as good as using an Alps set up, but it does work, and can help with those odd one offs that no-one will ever do commercially.
If I can help further, please let me know, and if you wish I could send you a seriousy off topic photo of some model railway wagons I did using the system
Graham Evans