I understand what you mean... you want to track your beats into Acid individually (I presume you only have a stereo input on your soundcard) and have them all line up in sync without having to edit the start of them all. I use cubase, but the principle will be the same:
On mpc:
Sync Out:X (Master) [the midi out port u are using]
Mode: Midi time code
Frame rate: [set this to be the same frame rate as Acid, Cubase detects and sets this automatically for you]
Send MMC: on or off (let's the mpc control the time cursor if on)
In Acid set it to external sync using midi timecode.
Set the tempo in Acid to be exactly the same as the tempo in your mpc.
Hit play on mpc and it should all sync up nicely

NB: It takes at least a bar to sync up perfectly after hitting play, so on your mpc create an empty 'sync' sequence that is 4 bars long and put it at the beginning of your mpc song when tracking.... so everything syncs up before your track begins for real.