YES..it is possible..You just need to see the line number for aux port by using "sh line"..Configure the "interface async x" (where x is the line number for AUX port) same as on 2651..
Now you don't need to use "autoexec ppp" under the line for ppp.you can use "autocommand ppp" or "autoselect ppp" depending on the use...You can use following line config too.
line aux 0
modem dialin
transport input all
flowcontrol hardware
modem autoconfigure discovery
autocommand ppp