Try two macros like so:
The one above will tell you if your job ability timers and TP are all ready for it.
- /recast "Sneak Attack"
- /recast "Trick Attack"
- /echo <tp>
You might also wish to warn your party so they don't move while you're doing this, but keep in mind that adding a line talking to your party can get very annoying with repeated usage, especially if it tries to say something cutesy.
- /ja "Sneak Attack" <me> <wait>
- /ja "Trick Attack" <me> <wait>
- /ws "Viper Bite" <t>
I forget if the timing on <wait> is enough as is, but you can adjust it as needed with a number like <wait5> if I'm not mistaken. You can change the weapon skill as needed, but you'll want to use a good physical weapon skill - weapon skills like Cyclone won't work with Sneak/Trick Attack unfortunately.
While forums are great places to ask for advice, you might also find community websites like FFXIAH, BGwiki, and FFXIclopedia useful, especially if you're trying to find out something like whether a particular weapon skill counts as physical to work with Sneak Attack, or what the price on that shiny new dagger is.