Mavic UST rims build up very nicely.
Just make sure you have the correct spoke length and that you know how to lace a wheel before you try.
I use DT threadlocker on the eyelets. It sets up pretty quick. It also seems to eat at yous skin a bit. I won't come unwound though which is nice.
If you are nervous you could dry fit the wheel before you add any threadlocker. Buy the Park Tool for the Mavic Eyelets or you won't get them tight enough.
This is perhaps the most tedious of all rims to build with but I do believe that they are more than worth the extra effort.
I can't wait for the 09' Mavic rims.. They are sure to build a 29" version.
There will also be more UST 29" tires by then too.
btw.. I heard Chris G say that he is considering building a 29er this week.
There must be something to this 29er thing??