I use:

/mark attack1 <mo>

...attack2...and up to 5. The <mo> is a mouse over so I don't actually have to switch targets. The only thing about this is if a lot of mobs are close together, you can mismark stuff. Some would argue that you only need to mark 1 or maybe 2 but to each their own really. If you do decide to mark only 1, you can tie it to your shield lob so:

/party Attack target 1!
/mark attack1 <t>
/ac "Shield Lob" <t>

p.s. ...but you use a controller so...this probably won't help you much.