Bluestrike have written a very good article about how to bulk load which is available on the mainpage. (Too bad it wasn't available when I learn bulk loading) Here I will like to share some personnal experience about the DX coding.
For those who do not know what is DX coding, it is the alternating black and silvery matrix found on any modern 35mm canister. the pattern will tell your camera infomation about the roll of film like its ISO speed and some other less important ones.
If you Bulk load films using used canisters like Bluestrike did in the article, the best used canisters you want to get will be used canisters of the kind of film you are loading, in this way both the labeling and DX rating are already done perfectly. e.g. if you are loading Velvia, getting the used canisters of original Velvia roll film will be the best.
But canisters of slide films are rare since folk only shoot negatives. So unless you ask Canister from pro labs it is unlikely you can have that luxury.
So the next best will be using canisters of film with the same DX coding. Since most cameras don't have the sensors for the second roll of the matrix (which tells the no. of exposure and latitude), this just means film with the same ISO speed. So you will want to use ISO 50 canisters for Velvia (RVP), ISO 100 canisters for Provia 100F (RDP) and so on.
Making the canisters DX labelled correctly will save you the trouble of manually setting the ISO after loading every roll. That will be important if you need to reload fast and prevents you from forgetting to set ISO and have the whole roll shooted under or over.
Some more most P&S cannot manually set ISO at all, although I doubt there will be any clubsnaper shooting bulk loaded slides with a film P&S.
but the world is not as good as you think...
The empty canisters you get from labs are mostly ISO200 with some 400s and few 100s. unless you go to pro labs these are about all the speeds you will get.
So if you are loading RVP or RDP rolls, chances is that you will be extremely short of ISO 50 or 100 canisters. For 400 canisters the situation will be much better but you still need to get at least 60 random empty canisters in order to get 20 of 400s that you need for one tin of Provia 400F (RHP). And there will be a lot of useless ISO 200 canisters laying around.
So what to do if you don't have enough canister of the speed you want?
Relable those ISO 200 canisters!
From the diagrams above you will notice that the DX lable for ISO 200 is very similiar to that of ISO 50 and 100. The only difference is that ISO 50 and 100 have one more box insulated (black painted). So what you have to do is to cut a piece of scotch tape to insulate (stick on) that respective box and get the canister correctly DX coded as ISO 50 or 100.
To convert the DX lable of 200 to 400 is much more work. I have to insulate (tape) two boxes and ground (scratch away the black paint) one box. Luckly 400 canisters are not really that rare to find, so I never actually did this before. Thanks you Kodak for pushing your MAX film. (25% OF YOUR PICTURES WILL BE IMPROVED! Yahoooo!!! )
Hope someone will find this useful