I'm asking the same question here also.......
viewtopic.php?f=31&t=38364
Have you read this?(read the bold part)
Setting the Acceleration Enrichments
In addition to the 'regular' acceleration enrichments, also check the X-Tau enrichments.
MegaSquirt-II™ (or MicroSquirt®) has blended MAPdot/TPSdot abilities for acceleration enrichment. You can select the proportion of each using the slider in the 'Tuning/Acceleration' dialog in MegaTune (the variable is called Tps_acc_wght in the code). If you choose 100%, you get accel enrichment based on TPS only, if you choose 0%, you get accel enrichment based on MAP only. Of course you can set it to any integer between these (99%, 98%, 97%, ... 3%, 2%, 1%, etc.) and get 'blended' accel enrichment.
The default values are a good place to start (especially if your req_fuel is somewhere between 10 and 20 milliseconds). (To convert v/s (used with older versions of MegaTune) to %/s, assume that 0%=0 Volts and 100% = 5 Volts (which isn't quite true, but it is a start), then 1.0 v/s = 20 %/s, etc.)
The values on the upper right are the TPS based values (as noted by the heading above them), those on the upper left are the MAP based values.
The two vertical columns show the current TPSdot and MAPdot values, with the recent peaks 'tell-taled' in red.
Larger values in the "Value (ms)" entries increase the amount of accel enrichment. Smaller values decrease the amount of accel enrichment.
The slider chooses the percentage of MAP versus TPS, somewhere between 30% and 60% is good for most installations. Some installations may need to use values outside this range to solve specific issues.
This is how mine came with when I opened up the program.....(seemed real high as noted by Matt C.) I think the factor might/should be x 20 when converting volts to % ? (maybe?)

My VW Bus and MS pix
CLICK
Running on MS since July 22/05,
MSnSExtra July/06 EDIS Aug/06,
now MS-II July 1/10.