Thanks.
I managed to figure it out from reading several things. Your posting was very helpful. I will post what i did here for others.
First read the posts above for the basics, then for custom fields.
open your system/cp/cp.mt_import.php file
around line 50 find var $extra_fields = 0; and change the number to how many custom fields you have.
Then in your txp form you are using to create the export use this format
<txp:if_custom_field name="address">EXTRA FIELD-1: <txp:custom_field name="address" />
<txp:php>echo "-----"."\n";</txp:php></txp:if_custom_field>
<txp:if_custom_field name="city">EXTRA FIELD-2: <txp:custom_field name="city" />
<txp:php>echo "-----"."\n";</txp:php></txp:if_custom_field>
<txp:if_custom_field name="province">EXTRA FIELD-3: <txp:custom_field name="province" />
<txp:php>echo "-----"."\n";</txp:php></txp:if_custom_field>
substituting the name of your custom fields obviously
couple of other tips which would have helped me at the end of each complete entry (article) there needs to be 8 dashes and a carriage return. This is important if the carriage return is not there the import will fail.
If you are importing categories be sure to assign a category group to your weblog first as well as the custom fields you will be importing. When you use the utility you can map which EXTRA FIELD belongs to which custom field.
Another useful bit. If you are using RSS_unlimited categories on your textpattern site (as many people did) here is a little hack you can use to output all of the categories your article is filed under. Not sure how great it would work if you have parent categories.
Go to admin > plugins and edit the rss unlimited plugin
We are going to alter the rss_unlimited_categories_filedunder portion of things. Warning this will temporarily mess up your site if it is live but you can output your info and then change it back quickly after. Speaking of which copy the text of the plugin and paste it into a blank text editor doc so you can quickly restore to the original.
Around line 173 you are looking for
$cats[]=tag(htmlspecialchars($b['title']),'a',' href="'.$path.'" title="'.htmlspecialchars($b['title']).'"');
What this is doing is outputing a link to the category with its name. All we want is the basic category name. So we will change this tag to
$cats[]=$b['name'].n;
This will export just the name of the category when we use the tag.
Then in our export form we will use this
PRIMARY CATEGORY: <txp:rss_uc_filedunder break="CATEGORY: " />
The break is meant to be something like li but it works well for our purposes.
I know that is a little long but hopefully it helps someone else out there.