HSER revisited

[skimask]

This will place the hex value of $ab into a0, correct?

Should do it.

What if I'm recieving several bytes such as $aa $ab $ac $ad etc etc and I want them in a1 a2 a3 a4 etc?
HSERIN [HEX4 ao, a1, a2, a3, a4]
or do I need multiple lines?
HSERIN [HEX4 a0]
HSER [HEX4 a1] etc etc.

Your first example would almost work, except it should be like this:
HSERIN [ HEX2 a0, HEX2 a1, HEX2 a2 ]
HEX2 for bytes
HEX4 for words
And multiple lines/statements would work too.