Yes, you can do this. The knack you need is the concept that there are two ways of getting tables out of the table server. One way is ..
FROM TABLE A
The other way is
FROM (SELECT col as name1, col2 as name2 FROM ...) B
Notice that the select clause and the parentheses around it are a table, a virtual table.
So, using your second code example (I am guessing at the columns you are hoping to retrieve here):
SELECT a.attr, b.id, b.trans, b.lang
FROM attribute a
JOIN (
SELECT at.id AS id, at.translation AS trans, at.language AS lang, a.attribute
FROM attributeTranslation at
) b ON (a.id = b.attribute AND b.lang = 1)
Notice that your real table attribute is the first table in this join, and that this virtual table I've called b is the second table.
This technique comes in especially handy when the virtual table is a summary table of some kind. e.g.
SELECT a.attr, b.id, b.trans, b.lang, c.langcount
FROM attribute a
JOIN (
SELECT at.id AS id, at.translation AS trans, at.language AS lang, at.attribute
FROM attributeTranslation at
) b ON (a.id = b.attribute AND b.lang = 1)
JOIN (
SELECT count(*) AS langcount, at.attribute
FROM attributeTranslation at
GROUP BY at.attribute
) c ON (a.id = c.attribute)
See how that goes? You've generated a virtual table c containing two columns, joined it to the other two, used one of the columns for the ON clause, and returned the other as a column in your result set.