Custom USB layout & sysinstall (Starting FIXIT)

[rank1seeker at gmail.com]

So, I downloaded USB stick .img
Instead of just writing it with dd, I've mounted and dumped it, as I wanted 
custom USB stick, layout.

To cut it short.
Bootable img file appears as ad0s2a instead of ad0a.
Once I boot from BIOS->USB stick->slice 2, I enter sysinstall successfully.

Now I wana enter into FIXIT, from sysinstall.
And I get "No USB devices found!", as well as, at all other parts, of 
sysinstall, that search for USB device.

Other parts of sysinstall, DO list ad4 (my HDD) and da0 (my USB stick) 
correctly.


I think sysinstall has hardcoded command, to mount da0a and doesn't see 
da0sxa, at all.

So how do I do it manually?
Emergency Holo Sh is no go.


Maybe this part of code is responsible, from file 
/usr/src/usr.sbin/sysinstall/devices.c:
Code:

/*
 * Find all devices that match the criteria, allowing "wildcarding" as well
 * by allowing NULL or ANY values to match all.  The array returned is 
static
 * and may be used until the next invocation of deviceFind().
 */
Device **
deviceFind(char *name, DeviceType class)
{
    static Device *found[DEV_MAX];
    int i, j;

    j = 0;
    for (i = 0; i < numDevs; i++) {
        if ((!name || !strcmp(Devices[i]->name, name))
            && (class == DEVICE_TYPE_ANY || class == Devices[i]->type))
            found[j++] = Devices[i];
    }
    found[j] = NULL;
    return j ? found : NULL;
}

PS:
Options --> Rescan Devices, in sysinstall don't work.

Could I start fixit, from loader prompt directly, so I wouldn't even have 
to eneter sysinstall, as I don't need it at all to install FreeBSD?