Conditional assist?

I have been trying but I can't seem to make it work.. Is there anyway to assist based on conditions like casting?
I have tried:
/assist [exists, harm, nodead, target=focustarget]
and
/assist [exists, harm, nodead] xxxx

None seem to work.. I guess I can use target=focustarget on my casts rather than an assist but I like having the target actually targeted. My issue is if I target a friendly target while attempting to continue casting the assist will target the friendly target and screw things up. Stickying targets with macros proved to be an issue in pvp so I don't want to continue doing that. If this isn't possible do you guys have any other suggestions?

i believe the correct syntax is /assist [target=focustarget,exists,harm,nodead]

Still does not work. Think I am going to post on the wow macro forums and see if theres a chance of getting the functionality added some day.

/cast [target=focustargettarget,help,nodead,exists] Regrowth; [target=target,help,nodead,exists] Regrowth; [target=player] Regrowth
I use this for my healing macro, it works as intended.

Ahh that works. Thanks Opt. I realized my error with the macro was thinking that I could check to see if the focus' target was an enemy for assisting but it can only check to see if the person I am assisting exists and such.

I actually got a response on the wow macros forums from Cogwheel (the macro pro) and he gave me this solution. Not sure which I want to use now though.

/stopmacro [target=focustarget, noharm] [target=focustarget, dead]
/assist focus

Depending on the complexity of macros this is probably overkill and waste too many characters so you could even stop at noharm.

EDIT: I realized this actually doesn't work because it then wouldn't cast either. As Cogwheel said we need a continuemacro command.

Are you assisting your focus or its target? Did you try:
/assist [target=focus, harm, nodead]

If that's not it, can't you use target instead of assist?
/target [target=focustarget, harm, nodead]

By the way, "help" and "harm" implies "exists". ;)